Preheat the oven to 350°F (175°C).

In a large saucepan, heat a tablespoon of avocado oil over medium heat. Chop sweet potatoes into 1-inch cubes, along with onion and green pepper. Sauté for 8-9 minutes until softened, adding minced garlic in the last 1-2 minutes.

Grease a 9x13-inch casserole dish. Spread the sautéed mixture evenly across the bottom.

In the same saucepan, add the turkey sausage and sauté until fully cooked, about 5-7 minutes. Break sausage into smaller pieces and mix with sautéed vegetables in the casserole dish.

In a large bowl, whisk together eggs, milk, fresh thyme, salt, pepper, and shredded cheese until smooth.

Pour the egg mixture evenly over the vegetable and sausage layer in the casserole dish. Stir gently to integrate.

Bake for 40-45 minutes. The casserole should be firm to the touch; cover with foil if browning too quickly.

Remove from the oven and let cool for about 15 minutes before slicing and serving warm.