Preheat oven to 450°F (230°C)
Line a baking sheet with parchment paper
In a bowl, whisk together 2 cups all-purpose flour, 1 tablespoon baking powder, 1 tablespoon sugar (optional), and 1/2 teaspoon salt
Cut 1/2 to 3/4 cup cold unsalted butter into small cubes (or grate frozen butter)
Rub or cut butter into flour until the mixture looks like coarse crumbs
Stir in 3/4 to 1 cup cold milk (start with less, add as needed) until a soft dough forms
Turn dough onto a lightly floured surface and gently fold 2 to 3 times
Pat dough to about 1/2 to 3/4 inch thickness
Cut biscuits with a floured biscuit cutter and place on the baking sheet
Gather scraps, re-pat, and cut again (avoid overworking)
Bake 10 to 14 minutes, or until tops are golden brown
Cool 2 to 5 minutes before serving