cold unsalted butter.

Cold butter creates small pockets of fat in the dough. When baked, the water in the butter evaporates, creating steam that lifts the dough layers, resulting in a flaky texture.

Unsalted butter typically lasts 2-3 weeks in the refrigerator. Because it lacks salt (a preservative), it has a shorter shelf life than salted butter.

Yes, but you should reduce the added salt in the recipe by about 1/4 teaspoon per half-cup (113g) of butter used.

Spoiled butter will have a sour or rancid smell, a pale or discolored appearance, and a sharp, unpleasant taste.

Use a sharp, cold knife to slice the stick lengthwise into four quarters, then cut across the strips to create small, even cubes.

Yes, butter freezes very well. Wrap it in an extra layer of foil or a freezer bag to prevent freezer burn and odor absorption.

Cold vegan butter sticks or solid coconut oil (chilled until firm) are the best substitutes for maintaining a flaky texture.

Unsalted butter allows the baker complete control over the salt content and is generally fresher because salt is often added to extend shelf life.

Chill your mixing bowl and flour beforehand, and if the dough feels warm, refrigerate it for 15-30 minutes before continuing.