breakfast casserole

Ingredients

• 12 oz sausage links
• 1 tbsp olive oil
• 5 eggs
• 1 1/2 cup whole milk
• 1 tsp ground dry mustard
• 1 salt and pepper
• 4 cup frozen hashbrowns, thawed
• 1 1/2 cup cheddar cheese, shredded, divided
• 1/2 minced onion
• 1 each of mushrooms or whatever you want.