Preheat your oven to 350°F (175°C) and grease a 9x13-inch casserole dish.

In a Dutch oven, heat avocado oil over medium heat. Add diced onion, green pepper, and sweet potatoes, sauté for 8-9 minutes.

Transfer the sautéed vegetables evenly into the greased casserole dish.

In the same Dutch oven, cook the turkey sausage over medium heat until fully browned, about 5-7 minutes.

Whisk together the eggs, milk, fresh thyme, salt, pepper, and cheddar cheese in a large mixing bowl.

Pour the egg mixture evenly over the sausage and veggies in the casserole dish and stir gently.

Bake in the preheated oven for 40-45 minutes, until the center is set and slightly puffed.

Let the casserole rest for 5-10 minutes before slicing and serving warm.