I have a question about the recipe "Alice Medrich's Best Cocoa Brownies" from Genius Recipes. The butter in these sometimes separates and I don't know why. I've made this recipe at least a dozen times, but every once in a while the batter is more of a solid than it is a liquid. And then as it bakes, the butter rises to the top and they just end up sort of funky (in both taste and texture). I am confident that I'm making the recipe correctly. The only thing that varies ingredient-wise is which cocoa powder I'm using. What could be causing this?