Preheat the oven to 350°F. Grease a 9x9 or 7x11 baking dish.
Brown the sausage in a large skillet, breaking it into crumbles.
Drain off all but a little of the grease.
Add the onion and bell peppers and cook for 3 to 4 minutes, until they start to soften. Stir them into the sausage.
Spread the sausage mixture in the baking dish and top with the cheddar.
Whisk the eggs, sour cream, cream, salt and pepper until smooth. Pour it evenly over the sausage and cheese.
Bake for about 35 minutes, until the edges are set and the center barely jiggles. Ovens vary, so check early.
Garnish with sliced green onions and serve with avocado, sour cream or salsa if you like.