Cocoa powder can be substituted in baking for unsweetened baking chocolate: replace 1 ounce of chocolate with 3 tablespoons of cocoa plus 1 tablespoon oil or shortening. The acidity of natural cocoa will react with other ingredients to act as a leavener.
To make a cup of delicious hot cocoa, mix 2 or 3 teaspoons cocoa powder with 2 or 3 teaspoons sugar and 1/2 teaspoon vanilla extract. Add a few drops of water to the mixture and stir to make a paste. Pour 8 ounces of milk on top of the paste and heat.
Cocoa powder also adds a lovely depth to chili, and can be used to tone down chili that’s a bit too hot. The addition of cocoa adds a subtle richness to mole sauces.