Patty out breakfast sausage into to about 7 or 8 small patties. Place patties into skillet and cook at medium high heat until seared on both sides and cooked thoroughly in the center.
Remove patties from skillet.
You should be left with 4 or so tablespoons of grease in the bottom of your skillet. If you feel there is not enough grease, you can substitute with a couple tablespoons of vegetable oil or butter in order to make your roux.
Add flour to your skillet until all visible grease is soaked up. If you want to make a slightly bigger batch or you want thicker gravy, you may add flour until the mixture begins to form little balls in the bottom of your skillet.
Cook roux mixture for about three minutes while constantly stirring. I use a three tonged granny fork to mix my gravy. You can also use a regular fork or whisk.
Add 2-3 cups of your milk and stir on medium to medium-low heat.
Once mixture starts to thicken turn off heat and continue stirring until your desired thickness. Salt and pepper to taste.
If your gravy turns out thinner than you want simply turn the heat back on and continue stirring. If you really have trouble you can stir in a couple of teaspoons of 50/50 cornstarch/water mixture to your gravy.
If it turns out thicker than you want, stir more milk into your gravy.
At the very end I crumble the cooked sausage back to my gravy for extra flavor and texture, but this is completely up to you.