Step 1

Preheat oven to 425°. Whisk baking powder, salt, and 2 cups flour in a large bowl to combine. Using a pastry cutter or your fingers, work chilled butter into dry ingredients until mixture resembles coarse meal. Using a wooden spoon or fork, mix in sour cream and milk until a shaggy dough forms.

Step 2

Turn out dough onto a lightly floured surface and knead a few times just to bring together. Roll out until ¼" thick, then fold in half. Roll dough out again until ¼" thick, then fold in half again. Repeat once more, rolling out to a ¾"-thick round.

Step 3

Punch out biscuits as close together as possible with cutter. Pat scraps together and punch out more biscuits; repeat until you can’t cut out any more (you should have 12 total). Transfer biscuits to a parchment-lined baking sheet, spacing 1" apart, and bake, rotating sheet once, until golden brown and baked through, 10–12 minutes. Brush biscuits with melted butter.

Step 4

Do Ahead: Dough can be made 1 day ahead. Cover and chill, or freeze up to 1 week.

Step 5

While biscuits are baking, cook sausage in a medium saucepan over medium heat, stirring occasionally, until cooked through and starting to brown, 5–8 minutes. Transfer to a small bowl with a slotted spoon.

Step 6

Add butter to drippings in pan and melt over medium. Whisk flour into butter mixture and cook, whisking constantly, until roux is very smooth and starting to bubble, about 2 minutes (don’t let it color; this is a white gravy).

Step 7

Gradually add milk, whisking until incorporated. Reduce heat to medium-low and cook gravy, still whisking, until thickened, 8–10 minutes. Stir in sausage; season with salt and pepper.

Step 8

Serve hot biscuits with gravy alongside for spooning over top.