INGREDIENTS
2 sticks (8 ounces) unsalted butter, plus more for the pan
3/4 cup powdered sugar
2 cups all-purpose flour
1/4 teaspoon coarse salt
INSTRUCTIONS
Place 2 sticks unsalted butter in the bowl of a stand mixer (or large bowl if using an electric hand mixer). Let sit at room temperature until softened.
Coat an 8- or 9-inch square metal baking pan with more butter.
Beat the butter on high speed with the paddle attachment until fluffy, 3 to 5 minutes.
With the mixer running, gradually add 3/4 cup powdered sugar and continue to beat until pale and fluffy.
Stop the mixer.
Sift 2 cups all-purpose flour into the bowl, then add 1/4 teaspoon coarse salt.
Mix on low speed until just combined.
Transfer to the prepared pan and pat to an even thickness no more than 1/2-inch thick.
Refrigerate for at least 30 minutes. Meanwhile, arrange a rack in the middle of the oven and heat the oven to 300°F.
Slice the dough into rectangles or squares in the pan. Bake until golden-brown and the middle is firm, 45 to 60 minutes. Let cool completely. Re-slice, if needed, before serving.