This recipe is based on Rose Levy Berenbaum’s excellent All Occasion Downy Yellow Butter Cake, adapted slightly to my own tastes and techniques.
Yellow Butter Cake
6 large egg yolks
1 cup milk
2 teaspoons vanilla
13 1/2 ounces (3 cups) cake flour, sifted
10 1/2 ounces (1 1/2 cups) sugar
1 tablespoon plus 1 teaspoon baking powder
3/4 teaspoon salt
12 tablespoons unsalted butter, softened
Begin by preheating your oven to 350˚F. Combine the yolks, about 1/4 cup of the milk and the vanilla, beating them lightly to blend. Pour the sugar into the bowl of a stand mixer, then sift the flour and the leavening together into the bowl. Add the salt. Turn the mixer on low and blend the dry ingredients for about one minute. Add the soft butter and the reserved milk. Slowly raise the mixer speed to medium and beat for 1 1/2 minutes until the batter is smooth and uniform. Scrape down the bowl.
Now begin to add the yolk mixture. Pour in about 1/3 of it, beat the mixture at medium speed for 20 seconds, then thoroughly scrape the bowl, paying particular attention to the bottom by the dimple. Continue on in that fashion until the entire yolk mixture has been incorporated. Divide the mixture between the two pans. Bake for 25 minutes, then check the layers. If the middle seems slightly sunken and mushy to the touch, continue to bake for another 7-10 minutes.
When fully baked, place the layers, in the pan, on a wire rack to cool. After 15 minutes, turn them out onto the rack to cool completely, about another hour.