Place chocolate bar or block on a cutting board and press down on it in several places with a large, sharp knife to break it up. For more finely chopped chocolate, hold the tip of the knife in place with your free hand and move the knife in an arc, making small chops as you go.
Creaming the butter for cakes and cookies is crucial. Beating the butter – often with sugar – before other ingredients are added creates air bubbles that make your baked goods high, light, and tender. Have butter at room temperature before creaming.
Whipping egg whites
Begin with eg whites at room temperature and a bowl that is absolutely clean and free of any fats or oils. Beat egg whites at moderate speed with a wire whisk or an electric mixer. When foamy, increase the speed. Beat until whites form stiff, stable peaks but are still moist and glossy.
Chill a metal bowl and the beaters for your electric mixer in the freezer at least 15 minutes before you begin. Pour cold whipping cream into the chilled bowl and beat on medium-high speed until medium-firm peaks form. Don’t overbeat or you’ll wind up with butter.
Source: Food Network Kitchens Cookbook