If you are using powdered cocoa, you can make the equivalent of one square of unsweetened chocolate by combining 3 tablespoons of cocoa and one tablespoon of vegetable oil.
To make four ounces of semisweet chocolate, combine 1/4 cup of cocoa, two tablespoons plus two teaspoons of vegetable oil, and one-quarter cup plus two teaspoons of sugar.
To make four ounces of semisweet chocolate, combine 1/4 cup of cocoa, two tablespoons plus two teaspoons of vegetable oil, and one-quarter cup plus two teaspoons of sugar.