In a large skillet (at least 10-inch) over medium-high heat, brown the ground breakfast sausage. Use a spoon to break it apart into small pieces as it cooks. Continue cooking until no pink remains and the sausage is nicely browned, typically 5-7 minutes.

Once cooked, if there is a substantial amount of rendered fat (more than 2-3 tablespoons), carefully drain off any excess, leaving just enough to create a roux with the flour.

Sprinkle the all-purpose flour evenly over the cooked sausage and remaining fat in the skillet. Stir thoroughly with a whisk or spoon, ensuring all the flour is incorporated. Cook for 1-2 minutes, stirring constantly, to cook out the raw flour taste. The mixture will form a thick, pasty roux.

Gradually pour in the warmed whole milk, starting with about half a cup. Whisk vigorously and continuously to incorporate the milk into the roux and prevent any lumps from forming. Once smooth, slowly add the remaining milk, continuing to whisk.

Bring the gravy mixture to a gentle simmer over medium heat, stirring occasionally. Let it simmer for 5-8 minutes, or until the gravy has thickened to your desired consistency. Remember it will thicken a bit more as it cools.

Stir in the freshly ground black pepper, salt, and the optional pinch of cayenne pepper. Taste the gravy and adjust seasonings as needed. Be cautious with adding extra salt, as many breakfast sausages are already quite salty.

Serve the hot, simple homemade sausage gravy immediately over warm, freshly baked biscuits. Enjoy!