Preheat your oven to 425°F (220°C) and line a baking sheet with parchment paper.
In a large bowl, whisk together the flour, baking powder, sugar, and salt.
Add the cold, cubed butter to the dry ingredients. Use a pastry cutter or your fingers to cut the butter into the flour mixture until it resembles coarse crumbs.
Gradually pour in the milk while stirring until a dough forms. Be careful not to overmix.
Turn the dough out onto a floured surface and gently knead it a few times until it comes together.
Roll out the dough to a 1-inch thickness and use a biscuit cutter to cut out biscuits. Place the biscuits on the prepared baking sheet.
Bake the biscuits for 12-15 minutes or until they are golden brown. Set them aside while you prepare the gravy.
In a large skillet, cook the breakfast sausage over medium heat, breaking it up into crumbles. Cook until the sausage is browned and cooked through.
Sprinkle the flour over the cooked sausage and stir well to combine, ensuring the flour coats the sausage evenly.
Gradually pour in the milk while stirring constantly. Continue cooking and stirring until the gravy thickens and comes to a simmer.
Reduce the heat to low and let the gravy simmer for a few minutes to allow the flavors to meld together. Season with salt and pepper to taste.
If the gravy becomes too thick, you can add more milk to achieve the desired consistency.
Split the biscuits in half and place them on serving plates.
Generously spoon the warm sausage gravy over the biscuits.
Serve immediately and enjoy the delicious combination of fluffy biscuits and savory gravy.