Preheat the oven to 350°F. Butter and flour one or two 9-inch cake pans. In a bowl, sift together the flour, baking powder, and salt and whisk to combine. Cream the butter and the 3/4 cup sugar using a heavy wooden spoon, a handheld mixer, or a stand mixer fitted with the paddle attachment. When the butter softens, switch to a whisk. Continue whisking, for about 5 minutes. Whisk in the egg yolks, one at a time, until the mixture is smooth.