Cook sausage in a large cast-iron skillet over medium-high, breaking into small crumbles, until browned and cooked through, about 8 minutes.

Sprinkle with flour; stir to coat and cook 2-3 minutes to remove raw flour taste.

Gradually stir in milk to prevent lumps; bring to a simmer.

Add salt, pepper, and garlic powder; reduce heat to medium-low. Simmer 5-7 minutes, stirring frequently, to desired thickness.

Taste and adjust seasoning; serve hot over buttermilk biscuits.