Coat inside of crockpot well with nonstick cooking spray or wipe down with vegetable oil.
Combine eggs, sausage, and cheese. Season to your liking with salt and pepper, then pour into prepared crockpot.
Chop biscuits into small bite-sized pieces, and place on top of the egg mixture.
Cook on high for 2 hours or on low for 4 hours.
To Make Gravy:
In a small saucepan, whisk butter and flour together until it just begins to turn a golden brown. Add in milk, salt, and pepper, and stir frequently over medium-high heat until it comes to a boil. Reduce to a simmer until thickened.
Serve gravy on top of the yummy breakfast casserole.