Almost every puff pastry recipe I know calls for equal amounts of butter and flour (by weight). They only vary in the amount of salt or lemon juice they use, or in the case of this recipe, by the types of flour used. In my experience, you don’t need to worry about cutting down the protein (gluten) by blending cake flour or cornstach into the all-purpose flour. If you treat the dough right, gluten won’t even be a factor.
Which gets me to the main point of this post: treat this dough gently. At least in the mixing stage. Don’t use a stand mixer, don’t use a hand mixer…don’t use your hands, don’t look at it, don’t even get near it. Run. Get to a minimum safe distance, squeeze your eyes closed, and bring the dough together psychically.
Yes, well, not psychically. But here’s the point: you want to avoid activating the flour’s gluten, which happens when you mix and/or knead dough. Gluten is a protein you see (actually it’s two different proteins), and proteins are long, snaky molecules. Mix them with water and toss them around a bit, and they grab hold of one another. Do it enough and they form long chains, eventually a mesh that’s very elastic (which is to say, it springs back when you pull on it). Great for chewy pizza dough. Not so nice if you’re trying to roll out a big lump of puff pastry.
So, mix but a little, knead but a little. If the dough’s a little clumpy don’t sweat it. You’ll roll’em right out later.