You can prep this the day ahead. Just give it a good stir again in the morning before you put it in the oven. Prep everythign in the same oven proof skillet for a one pot casserole. BEWARE: pre-cooking it in a cast iron pan might turn the potato mixture gray, which happend to a some readers. We suggest using a an oven safe pan that isn't cast iron.
NOTE: Not all shredded hash browns are created equal. Some are more firm while others are mushy. Ore Ida refrigerated shredded hash browns are very mushy. If you want your hash browns crispy, then we suggest using extra oil to fry the hash browns or buy the crispy pre-cooked patties.
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.