Add the sausage to a large frying or cast-iron pan over low to medium heat to help lightly brown and render the fat.
Continually stir the sausage to help break it up into smaller bitesize pieces until browned and cooked throughout. This takes about 6 to 8 minutes.
Remove the sausage and set it to the side on a plate.
Add the butter to the pan and wait for it to melt over low to medium heat.
Once melted, whisk in the flour until combed to form a roux.
Next, pour in the milk while whisking to combine the roux with the milk, and turn the heat to high to bring the mixture to a boil. It should become very thick, like an alfredo sauce.
Turn the heat down to low and cook while occasionally whisking until the starch flour taste is gone, which takes 4 to 5 minutes.
Add back in the cooked sausage and adjust the seasonings with salt and pepper.
Serve with optional garnishes of chopped fresh sage, thyme, and red pepper flakes.
Notes
Make-Ahead: You can make this recipe up to 2 days ahead for freshness. Keep cool until ready to use.How to Store: Cover and keep in the refrigerator for up to 4 days. You can freeze this, but the sauce may break, and you will need to rethicken it.How to Reheat: Add the desired amount of sausage gravy to a small saucepot and heat over low heat until hot. You may need to rethicken it with a small amount of roux or thin it with a few tablespoons of milk.Additional ingredients you can add to the sausage gravy would be fresh or dry sage, thyme, or red pepper flakes.The roux is activated in the milk once it comes to a boil.