I'm baking a cake using a cake mix and extra ingredients. It calls for 5 tbsp of butter, but I'm not sure which to use, salted or unsalted. What difference would it make??
Generally, you'll want to use unsalted. The amount of salt in salted butter can vary, so most recipes call for unsalted, and then have you add the exact amount of salt. Cake mixes have salt in them, so this would still apply.
Agree and +1 to Martha's answer, unsalted is generally preferred for baking.
Just wanted to add that if you only have salted butter and the recipe calls for unsalted then I would say don't worry too much. It's OK to use salted instead.