If you make a thick crêpe batter with flour into which you’ve sifted a small amount of baking powder, you’ll have pancake or waffle batter. But if you separate the eggs called for in a crêpe batter, add the yolks to the batter, and beat the egg whites and fold them into the batter, you’ll end up with light and luxurious waffles and pancakes with none of the soda taste that sometimes sneaks through in recipes that include baking powder. If you take the same ingredients in crêpe batter, increase the amount of butter, add sugar and a tad of baking powder, and work the ingredients in a somewhat different order, you’ll have madeleine batter. Madeleines are the little cakelike lemon cookies shaped like scallop shells that Proust made famous. They’re worth learning how to make because they’re easy and delicious and they cost about a dollar each in fancy pastry shops. The only downside is that madeleines require a special flat mold with scallop-shaped indentations, but this is a onetime purchase. It used to be that the only tricky part to making madeleines was getting them not to stick to the mold, but now you can buy nonstick molds that solve this problem. The molds, even nonstick versions, need to be brushed with softened butter to prevent sticking.