Preheat the oven to 350°F. Lightly coat an 8-inch deep-dish pie dish or baking dish with coconut oil or nonstick cooking spray.Heat the butter in a large skillet over medium heat. Add the onions and sauté until soft, 3 to 4 minutes.
Add the sausage and cook until evenly browned, 4 to 5 minutes. Drain and set aside.
In a large bowl, whisk the eggs, cream, garlic, salt, and pepper.
Spread the sausage and onion mixture evenly on the bottom of the prepared dish and top with the cheese. Pour the egg mixture over the cheese.
Bake for 35 minutes, until the eggs are set and the top is lightly golden brown.
Allow to cool for 3 to 5 minutes before serving. Leftovers can be covered and stored in the refrigerator for up to 4 days.
CALORIES: 394 | FAT: 33 g | PROTEIN: 21.8 g | TOTAL CARBS: 2.6 g | NET CARBS: 2.6 g