Cook the Sausage - Heat a large skillet over medium heat. Add the sausage and break into smaller pieces using a spoon. Cook until no longer pink and lightly browned, about 5 to 6 minutes.
Cook the Aromatics - Melt the butter in the pan. Add the onions, garlic, and thyme. Cook until fragrant and tender, 1 to 2 minutes.
Add the Flour - Sprinkle the flour, salt, and pepper over the sausage mixture. Stir and cook until the flour is absorbed, 2 minutes.
Simmer the Gravy - Slowly stir in the milk. Increase the heat to medium-high to bring to a boil. Lower the heat to a simmer and stir occasionally until the gravy is thick and can coat the back of a spoon, about 5 minutes. Taste and season with salt and pepper as desired.
To Serve - Serve with biscuits split in half with sausage gravy on top or other desired foods.
Notes
Gravy Yield: About 3 cups
Serving Size: 1/4 cup of sausage gravy
Make it Gluten-Free: Use cassava flour instead of all-purpose flour. Alternatively add a cornstarch slurry mixing 2 tablespoons of cornstarch with 1/4 cup of water. Add to the boiling milk, stirring until thickened, about 1 to 2 minutes.