To clarify butter, in a small heavy saucepan melt butter or margarine, without stirring, over low heat. When the butter is completely melted, there will be a clear, oily layer atop a milky layer. Slowly pour the clear, oily layer into a dish, leaving the milky layer in the bottom of the saucepan; discard the milky liquid.
Wash the saucepan. Return clarified butter to the saucepan. Add sugar, stirring until combined. Add lemon peel and lemon juice, stirring until sugar dissolves. Stir in brandy. Serve warm. Cover and refrigerate remaining butter for up to 1 week. Makes 1-3/4 cups.