Put a rack in the upper third of your oven and preheat to 425℉. Line a baking sheet with parchment paper or a silicone mat.
In a medium to large bowl, combine the 1 cup all-purpose flour, 2 teaspoons baking powder, and ¾ teaspoon salt.
Incorporate the ½ cup unsalted butter. I like to freeze the butter and grate it in. However, you can cube cold butter and work it in with a pastry cutter if your prefer. Either way, the butter should be in small crumbly chunks that are evenly incorporated into the flour mixture.
Stir in the 1 cup sourdough discard until the mixture just comes together.
Because everyone's starter is at a different hydration level, you will need to feel the dough. If all of the flour is able to be incorporated and the dough is moist but not too sticky, you can proceed. If the dough seems dry, add the 2 Tablespoons milk a little bit at a time until it comes together. If the dough is too sticky, add another Tablespoon or two of flour.
Put the dough on a lightly floured surface and pat into a rectangle about ½-inch thick. Fold the dough in half to form an inch thick slab of dough.
Using a 2½ inch biscuit cutter to cut the biscuits. Be sure to press straight down and don't twist. Cut the biscuits close together to get as many as possible out of the dough.
Bring the scraps together and repeat the process of pressing into a ½ inch thick piece of dough and folding it over. In total, you should get roughly 7 biscuits.
Place biscuits a couple of inches apart on the lined baking sheet. Bake for 20-23 minutes or until they are golden brown.