I make the entire casserole in a 12-inch cast iron skillet, but if you do not have one, you can use an oven skillet on the stovetop and then pour everything into an oven safe casserole dish. If you will be using the casserole dish, be sure to grease it before pouring the casserole in.
Warm some olive oil in your skillet over medium high heat and brown the sausage. Use a slotted spoon to scoop the browned sausage out of the pan, leaving the drippings behind. You’ll want 1-2 tablespoons of the drippings in the pan to cook the veggies – if you have more than that, you can drain some of the grease out.
After the sausage is browned, and removed from the skillet, add the onion, bell pepper, broccoli, and a pinch of salt to the skillet, cooking over medium high heat until the veggies are soft and sweet – about 5-7 minutes.
Add the garlic and spinach to the skillet and cook for 1-2 minutes until the garlic is fragrant and the spinach is wilted.
Next, the cooked sausage, veggies, and shredded potatoes and sweet potatoes need to be combined. I find this easiest to do in a large mixing bowl versus trying to stir it together in the skillet. Transfer the cooked veggies, sausage, and shredded potatoes to a large mixing bowl and combine well.
Return the sausage/veggie/potato mixture back into your cast iron skillet (or if you are using a casserole dish, pour the mixture into that instead), and spread out evenly.
In a liquid measuring cup, measure out the Dairy Free Cream Cheese Sauce liquids, and then whisk in the nutritional yeast, potato starch, and seasonings until smooth. Pour the Dairy Free Cream Cheese Sauce over the sausage/veggie/potato mixture in the skillet. It should spread evenly but you can use a spoon to ensure everything is covered well.
Bake the casserole, uncovered, at 400 degrees for 45 minutes. The top will be golden brown. Let the casserole rest on the counter for 5-10 minutes before cutting in.