Preheat your oven to 350°F (175°C).

Lightly grease the casserole dish with avocado oil or cooking spray.

Heat 2 tablespoons of avocado oil in a Dutch oven over medium heat. Sauté the chopped onion and green pepper for 8-9 minutes.

Add the cubed sweet potatoes to the sautéed mixture. Cook for an additional 5-7 minutes. Add minced garlic in the last minute.

Spread the cooked vegetable mixture evenly across the bottom of the greased casserole dish.

In the same Dutch oven, add turkey sausage and cook until browned, about 5-7 minutes. Drain excess liquid and mix into the casserole dish.

In a large mixing bowl, whisk together eggs, milk, thyme, salt, and pepper. Stir in shredded cheese.

Pour the egg mixture over the sausage and vegetable layers. Gently stir to combine.

Bake in the preheated oven for 40-45 minutes until center is firm and top is lightly golden.

Let the casserole rest for 15 minutes before serving.