Biscuits and Gravy

Name: Biscuits and Gravy
Ingredients: 2 sticks (8 ounces) unsalted butter, divided; 1 cup cold buttermilk; 3 cups all-purpose flour, plus more for dusting; 2 1/2 teaspoons baking powder; 2 teaspoons granulated sugar; 1 1/4 teaspoons kosher salt; 1/2 teaspoon baking soda; 1 pound raw pork breakfast sausage; 1/3 cup all-purpose flour; 3 cups whole or 2% milk, plus more as needed; 1/4 teaspoon freshly ground black pepper, plus more as needed; 1/4 teaspoon kosher salt, plus more as needed; Hot sauce, for serving (optional)