Heat a large pan over medium-high heat. Add the oil, chopped onions, diced apples, and diced sweet potatoes to the pan. Stir to combine and sauté until the apples and onions start to brown, stirring occasionally, about 10-15 minutes.

Add the cooked sausage and chopped spinach to the pan, stir, and set aside.

In a large bowl, combine the milk, eggs, dry mustard, and salt. Whisk until combined. Set aside.

Grease a 9 x 13 casserole dish. Tear the whole grain bread into large chunks and spread it in an even layer on the bottom of the casserole dish. Top with onion, sausage and veggie mixture. Make sure to spread it evenly over the bread.

Then pour the egg and milk mixture evenly over the dish.

Cover and let it sit in the refrigerator overnight.

In the morning, uncover the dish and crumble the goat cheese on top (if using). Bake the casserole on 350 degrees for about 45 minutes or until all of the egg has been cooked. Enjoy!