Can you use light brown sugar in place of dark brown sugar?
Herein, when a recipe calls for brown sugar should you use light or dark?
The difference between light and dark brown sugar is the amount of molasses that's been added to the sugar. Light brown sugar is subtle, while dark brown sugar has a more intense molasses flavor. You can use them interchangeably in any recipe that calls for brown sugar, per your preference.
Just so, can I use dark brown sugar instead of light brown sugar in chocolate chip cookies?
You can substitute dark brown sugar for the light brown sugar in the cookie recipe, however the cookies will be slightly darker in colour and will have a slightly more caramelly/toffee taste to them.
Just add a tablespoon of molasses to a cup of light brown sugar to turn it into dark brown sugar. This will give you the real deal. If you don't have molasses, use a tablespoon of maple syrup instead, or just use your light brown sugar in place of the dark brown sugar that's called for.