In a large skillet, cook the sausage over medium heat until browned. Break up the meat as it cooks.
Sprinkle flour over the cooked sausage, stir, and cook for 2 minutes.
Gradually add milk while stirring constantly. Increase heat to medium-high, bringing the mixture to a boil. Reduce heat and simmer until the gravy thickens, about 5 minutes. Season with salt, pepper, and sage.
Preheat your oven to 375°F (190°C).
Arrange biscuits in a single layer in a 9×13 inch baking dish. Pour the sausage gravy over the biscuits.
Bake in the preheated oven for 25-30 minutes, until the biscuits are golden brown.