Preheat oven to 350 degrees.
Coat the inside of the mushrooms with the ghee. Place mushrooms in a baking dish and place in the oven. Bake for 5 to 8 minutes, until the mushrooms have softened.
In a large skillet over medium heat, heat coconut oil. To the skillet, add the next 5 ingredients (turkey through salt and pepper). Cook for 10 minutes, until turkey is cooked and vegetables are tender. To the turkey mixture, add the marinara sauce and stir.
Spoon the turkey mixture into the mushroom caps and top with cheese. Place the mushroom pizzas back in the oven for 10 minutes, until cheese has melted. Serve warm.