You can prep this the day ahead. All you need to do is to give it a good stir again in the morning before you put it in the oven. If you have an oven safe skillet you can prep and bake everything in the skillet for a one pot casserole. Our favorite pan to use is a large cast iron skillet.
Heat pan on medium-high heat, cook bacon until browned. Add onions and garlic, cook until soft, about 1 minute. Add sausage and cook until browned and cooked, about 5 minutes. Break apart sausage into small chunks as you cook it.