The next time you run out of brown sugar, check your pantry again before you head to the store—if you have granulated white sugar and molasses, you have the makings of brown sugar.
For every cup of brown sugar needed, add 1 Tbs. molasses for light brown or 2 Tbs. for dark brown to 1 cup of granulated sugar. Combine with an electric mixer on medium-low to medium-high speed (start slowly and gradually increase the speed) until the molasses is incorporated and the mixture becomes fluffy brown sugar. This may take as long as 10 minutes—just keep at it until most of the molasses balls are blended in.