I have a question about the recipe "Angel Food Cake with Heath Bar Whipped Cream Icing" from Merrill Stubbs. Do you sift the flour before you measure it or after?
It depends how it's worded. In this case, you sift and then measure. If it said one cup flour, sifted, it would mean measure and then sift.
This is why I prefer weighing ingredients - no confusion!
When baking, optimally the ingredients are measured by weight, not volume. However, most recipes still call for volume measurement. The general method for measuring flour and other loose dry goods is spoon then scrape to level the cup. If the recipe says 'x cups flour, sifted', then sift after measuring.