It might not seem like it would really matter. What's a little salt? But trust me on this one: it does. Unsalted butter is the difference between a batch of cookies that turns out perfectly and one that tastes bland — or salty (even worse). I'm curious: do you have a favorite brand of unsalted butter for baking?It's hard to know how much salt a stick of regular butter might contain. Using unsalted butter takes out the guesswork and gives us more control over the ingredients going into a recipe. Plus it's the way recipe writers have developed their recipes and how they can ensure that whatever tasty treat you're about to make turns out just as delicious as they intended.
Leftover sticks of unsalted butter can be stored for months in the freezer, which is handy if you're not a frequent baker. Even portions of sticks can be saved this way. Just wrap the leftover bits in wax paper to protect any exposed surfaces from freezer burn.
Save your regular butter for biscuits. When it comes to cookies and cakes, unsalted butter is the way to go.