Making Crème Mousseline

Crème mousseline — also known as German buttercream — is a silky and decadent combination of pastry cream and butter. It’s often used as a filling, though it works just as well as a frosting, as the “buttercream” moniker implies. The proportions for crème mousseline are 2 cups pastry cream to one cup very soft butter. Yeah, I know. Wow.

Here I am adding one cup of unsalted, cultured butter to 4 cups of pastry cream that I made with the full amount of sugar and twice the vanilla. I’m getting light-headed already.

I beat that in for about three minutes and it’s looking a little curdled, which is OK. So I’m pressing on with the second cup. Steady, Joe, steady.

After another three minutes or so of beating, this is the result:

A perfectly smooth and glossy mousseline/buttercream. Should yours still be lumpy, it could be because the butter was too cool when you started. That’s not a problem. Just let the mixture sit and warm until the butter softens completely, then beat — or whip — the mixture some more. In extreme cases where you have lots and lots of cool butter pieces, it’s OK to heat the mixture a little. Put it in a microwave-safe container and zap it for five seconds, stir, zap another five seconds until the mousseline is slightly warmed and the butter is utterly softened. Some butter may separate out when you do that, which is completely fine. Just dump the whole mess back into your stand mixer and apply the whip until it fluffs up as seen above.

For those who are curious about buttercreams but worry about syrup making, crème mousseline makes an excellent intro to the genre. You just combine everything and beat it. It’s also a nice way to recycle leftover pastry cream because the addition of lots of butter makes crème mousseline freeze-able. You’ll need to re-whip it once it thaws, but that’s no big deal. Overall it’s an eggier taste than a standard buttercream, but since when was that ever a problem?

I should add that some German buttercream recipes call for more butter, up to double the amount show here. That’s too much for me. You’d need to revive me with smelling salts.

48 thoughts on “Making Crème Mousseline”

  1. The texture looks awesome and perfect for so many things. Is this the same stuff in Bienenstich cake?

    1. The filling for Bienenstichkuchen is usually a vanilla pudding. I have never had one with buttercream, but it might be a tasty variation to try.

      1. It is a combination of vanilla pudding and butter
        1pkg vanilla pudding … Not the instant … Cook as told let stand to till it reaches room temperature .. Stir often
        1/2 pd unsaltet Butter at room temperature
        Cream butter and add vanilla pudding very slow spoon by spoon full.

        1. My mother-in-law taught me this method 30 yrs ago. Only difference was she added the tip of a teaspoon of cornstarch, she said to thicken it. And she set the pot of cooked pudding in a bigger pot of ice stirring it to cool while the butter was being beaten on the mixer. She said the key to it was both pudding and butter had to be at the same temp.

    2. Hi Justine!

      German bee sting cakes can be filled with whipped cream but more often have a pastry cream filling. Buttercream is not unheard of, nor is vanilla pudding.

      Thanks for the question!

      – Joe

  2. I made this for a Danube Wave Cake but didn’t know that it was Crème Mousseline! I discovered it was Mousseline a year or so later when I was reading a discussion about the difference between Swiss and Mousseline buttercreams. I was skeptical about the amount of butter that was in the Wave cake recipe because it just looked like way too much, so I stopped adding butter when the mixture felt stiffer than I ever thought buttercream should be. The pastry crème called for a lot of vanilla and almond extract, too, more than I was used to using, but I used it anyway because of the amount of butter to be added. It was so delicious I’ve used it since as a filling for cake and cookies many times. Very tasty stuff!

    1. Yes indeed! And you bring up an excellent point: the pastry cream you use should be good and sweet, and probably have extra vanilla since as you point out, it will be diluted by the butter. Thanks for the great comment!

      – Joe

  3. I love creme mousseline and yours looks amazing. My favorite use for it is to replace buttercream on cupcakes, because that luscious swirl on top of the cupcake is almost always too much of a good thing with classic buttercream.

  4. I’ve never tried creme mousseline. Certainly looks good from the pictures! What does it taste like? Is it heavy like buttercream or more of a light custardy feeling?

    1. Hey Jey!

      All I can say, lamely, is that it’s somewhere in between. You need to give it a try. It’s rich, so like buttercream it’s not meant to be eaten by the mouthful. As a filling or with fruit — as in a fraisier — it’s fantastic. Let me know what you think!

      – Joe

  5. This seems like it might be similar in texture to cooked flour frosting: a roux of flour and milk cooked into a paste, cooled, then sugar and cool butter beaten in until fluffy, plus vanilla and maybe chopped pecans. It’s an old-fashioned Southern thing; my grandmother used to make a version for her orange layer cake. I’m sure this is better-tasting though; more elaborate process and egg yolks and Frenchness and all…

    1. Hi Donna!

      I call that “heritage” frosting here on the blog. It’s in the pastry components menu under Icings and Frostings. Mousseline is quite a bit richer than that, though not as rich as buttercream. You should try it and see!

      – Joe

  6. Donna, I’ve made the cooked buttercream you’ve mentioned. It’s very tasty with a whipped cream like texture, though the texture looks more like an over-whipped cream; it’s not as smooth. I think the flour/butter roux base is to blame for the appearance. The mousseline appears very smooth but it’s a little heavier and is more buttery in flavor.

  7. It turns out that Latvian staple frosting for rich layer cakes has fancy name 🙂 We call it simply “boiled cream”, which is actually not precise, because real “boiled cream” is what everyone knows as pastry cream.
    I really love mousseline in genoise layer cakes, and they are not dry at all if properly assembled (enough jam and frosting between layers, and enough time before serving).

  8. Chef Joe you are a genius!! thank you for sharing such great recipes! I am going to try them this week. I am making rich cupcakes so do you thing that this creme mousseline will bee too rich? do you know a lighter frosting if the creme mousseline could be too rich for may rich to be cupcakes? thank you! I am so glad I found this page!

    1. Hey Ann!

      Mousseline cream will work great on a cupcake. Just use a thin layer…as you should with any real buttercream…and it should not be overwhelming. Let me know how it goes!

      – Joe

  9. BTW this cupcakes I am making are for a wedding and will be out for 6 hours or so….

  10. Awesome recipe and thank you for it. And if I had to describe the taste it would be unfrozen ice cream.

    1. That’s perfect, William. You’re completely right. Mrs. Pastry, who is sensitive about richness but adores ice cream, loves this. I shall remember that in the future!


      – Joe

  11. You’re welcome . Hey Joe if I may ask a question? Do you think you could make the same recipe using a Bavarian cream? Would the resulting mixture be any more stable because of the gelatin ?

    1. Hey William!

      Interesting question. I’m not sure that would work as well. Bavarian cream is a “still” custard (as opposed to a “stirred” on) that’s thickened with gelatin instead of starch. Think of what happens when you stir JELL-O, it gets loose but also stays sorta chunky. I don’t see it incorporating very well into a buttercream frosting, but then I’ve never tried it! If you do please let me know how it goes!


      – Joe

      1. I think that if you cool the Bavarian cream in an iced water bath, stiring it occasionally, untill it sets a little and then add butter, it will work.

  12. When would be a good time, and what’s the best way, to add flavors to this? I was thinking of making a caramel/dulce de leche version. 🙂

    1. The best point is the pastry cream making step. I’d say you could make caramel out of the sugar that you’d normally add to the milk and/or half n’ half. Swirl it in a pan over high heat with enough water to moisten it. Cook it to whatever stage of darkness you want, then carefully whisk in the milk, making sure are the caramel gets melted in.

      Let me know how it goes!

      – Joe

  13. Pingback: Bobo Birthday Cake
  14. Hi Joe,

    this crème mousseline/GBC is not only velvety and delicious, it is sturdy, too! I experimented with this GBC for a three-layer Pineapple Jam Crumble Cake (an attempt to reconstruct the Nastar Crumble Cake from a famous bakery in Jakarta).

    I was unsure at first. So I used more butter than suggested, but not to double, and the GBC was firm enough to support the yellow cake (your adaptation from Rose’s, Joe). To flavor it, I used vanilla bean and vanilla extract in the pastry cream as a background, and added lemon oil for a zing, which worked well with the pineapple theme.

    I remain a huge fan, Joe!


    1. Hello Katzies!

      I haven’t had a chance to respond to your email as yet — what an achievement! And yes, crème mousseline is very sturdy stuff is it not? Truly a fabulous cake. If there are leftovers, please mail a slice to me.


      – Joe

  15. Hi, Joe,

    If I wanted to make a chocolate crème mousseline, how much chocolate should I add? At what stage?
    (Is it even possible?)

    Thank you,


    1. Very interesting idea, Lara! You can do a couple of things. You can start with a chocolate pastry cream, or just beat about three ounces of cooled, melted chocolate into the finished buttercream. Or both! 😉

      Thanks for the question!

      – Joe

    1. Not that I’ve seen but I’d be keep to eat one of those!

      Definitely do it.

      – Joe

  16. Hey chef.. I wonder can I use this for fraisier? Will the cream be too heavy for the cake or will it be perfectly?if so how long am I suppose to leave the cake in the fridge before I can serve?

    1. Hi Nini!

      Yes, indeed this is the cream I recommend for a fraisier. The finished pastry needs to be refrigerated for a minimum of four hours, but overnight is best.


      – Joe

      1. This cream is what is commonly used in fraisier. Problem is fraisier is a cake so it needs to maintain its shape. if it sits at room temperature for a bit it starts to melt. I add 1 pack of gelatine while cooking the pastry cream to make up to 3. 5 cups of mousseline cream.

        1. Not a bad idea at all, CGB! Especially if you’re in a restaurant or pastry shop setting where your slices may need to sit for a while at temperatures above 70 degrees Fahrenheit.

          As with all creams and frostings that rely heavily on butter, the higher quality butter you use, the less you’ll have to worry about melting, since the lipids will tend to stay firmer, even as they get warmer. Of course that only works up to a point, but top quality butter does offer a little extra insurance in that department — not to mention fabulous taste!

          Excellent comment!

          – Joe

  17. hi chef,

    i made the pastry cream by your recpie and looks great, i am wondering when i need to add the butter, after the pastery get cooler or while its hot?



    1. Hi Amir,

      Sorry for the delayed response. You want to spread on little while it’s hot, to present a skin from forming.


      – Joe

  18. Can this be used for piping borders, flowers…. on cakes, cupcakes, etc? Is it stable enough to keep its shape?

    1. Hi Fabian. It firms beautifully when it’s chilled, but warm it’s not suited for piping, at least if you want really crisp edges. It’s a little too gelatinous for that. But by all means give it a whirl. I’d be curious what you think.


      – Joe

  19. My mousseline called for 1 cup of butter. It looked great until later on after being in the fridge for a couple of hours, it looked like it ‘broke down.’ When I re-mixed it, it seems to lose its consistency. What would have caused this? I expected it to be much firmer in texture due the the butter being chilled.
    Thanks for your time.

    1. Hey Tom!

      If you still have it, just put it back i the mixer and beat it, beat it, beat it. Eventually the temperatures will equalize and the whole thing will smooth out again (i.e. the emulsion will re-form). It could take 20 minutes or more…just keep going.

      Refrigeration is tricky with any butter-heavy concoction like this. All the various components behave differently when they get cold. But get all the pieces parts (fat, syrup, etc.) back on the same page, and you should have a spreadable mousseline once more!

      Cheers and have fun!


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