Preheat your oven to 350°F (175°C). Lightly grease the baking dish with olive oil or nonstick spray to prevent sticking.
In a large skillet over medium heat, cook the breakfast sausage, breaking it up into small crumbles with a wooden spoon or spatula. Continue cooking until the sausage is browned and fully cooked with no pink remaining.
Place a colander over a bowl and carefully pour the cooked sausage into it to drain off any excess grease.
Wash and chop your low-carb vegetables (see post for suggestions). If you’re using vegetables that release moisture (like mushrooms, spinach, or zucchini), lightly sauté them in the same skillet for a few minutes to remove excess water. Set aside to cool slightly.
In a large mixing bowl, whisk together the eggs and heavy whipping cream until smooth and well combined. Stir in the salt and pepper to season.
Add the cooked sausage, vegetables, and 1 cup of shredded cheese into the egg mixture. Stir gently until everything is evenly coated.
Pour the mixture into the prepared baking dish, spreading it evenly with a spatula. Sprinkle the remaining 1 cup of cheese over the top for a golden, bubbly crust.
Bake for 35–40 minutes, or until the casserole is puffed and the eggs are fully set in the center. Check for doneness by gently pressing the middle. It should feel firm, not soft or wet.
Remove from the oven and let the casserole cool for 5–10 minutes before slicing. Serve warm, optionally topped with a spoonful of sour cream, avocado slices, or fresh herbs.