Using your fingers, break the breakfast sausage up into small pieces into a large skillet, heat over medium heat and when it starts to sizzle, add the butter, cook stirring, until the meat is no longer pink. Add half the flour and stir until absorbed into the butter and coats the sausage, continue adding the flour little by little, stirring it around until it has all been used and the pan looks dry. The flour will just start to brown, about a minute more.
Slowly add 2 cups of milk, stirring constantly until it thickens, adding more milk as needed. This process can take up to 10 minutes, so don't add too much all at once, add as needed until you get a nice thick "gravy". If the sauce becomes too thick, add more milk in small amounts.
Once the gravy is nice and thick, add the Slap yo Mama or equivalent, thyme, sage, and black pepper. Stir, and taste. Adjust seasonings and serve immediately over warmed halved biscuits.