Preheat oven to 450°F; combine flour, baking powder, baking soda, sugar and salt in a large mixing bowl.
Cut (blend) cold butter into this mixture until it resembles crumbs; add buttermilk as you stir until dough forms.
Place the dough on a lightly floured surface; knead until the dough holds together; press the dough into a square; fold it over on itself several times.
Press the dough to 1-inch thick; cut out biscuits with a 3-inch cutter; reshape scraps to cut additional biscuit(s).
Place the cut-outs on an ungreased baking sheet; bake ~12 minutes, until lightly browned.
Brown sausage in a skillet over medium heat.
Sprinkle flour over the sausage; stir ~2 minutes.
Add milk slowly, whisking continuously.
Stir in salt, pepper and garlic powder; adjust to taste.
