A recipe calls for unsalted butter and then says to add 1/8 teaspoon salt. Why can’t I just use salted butter?

You could use salted butter if you really wanted to, but there are reasons to stick with unsalted butter for baking. First, you don’t know how much salt is in the butter, so it’s difficult to tell if you’re getting the same amount of salt in the recipe.

Second, one reason salt is added to butter is as a preservative. Unsalted butter tends to have a fresher taste, although it doesn’t keep as long. (If you stock up on unsalted butter, store it in the freezer.)

Since unsalted butter is so easily available, my advice to new bakers is always to follow the recipe exactly the first few times you make it. That’s the best way to ensure a good result.