Preheat your oven to 350°F (175°C) and lightly grease a 9x13 inch glass or ceramic baking dish. This helps prevent sticking!
In a large skillet over medium-high heat, cook the sausage until it's completely browned and no longer pink. Break it into crumbles as it cooks. Once done, remove it from the skillet.
In a big mixing bowl, whisk together the eggs, heavy cream, and minced garlic until they're well combined and slightly frothy.
Stir the coarsely grated zucchini directly into the egg mixture – no need to drain it! Then, add the coconut flour, baking powder, salt, pepper, and the optional red pepper flakes. Mix everything thoroughly until the batter is smooth and there are no lumps from the flour.
Gently fold the cooked sausage crumbles into your egg and zucchini mixture.
Pour the entire savory mixture into your prepared baking dish. Sprinkle the shredded Cheddar cheese evenly over the top.
Bake for about 40 to 45 minutes. You'll know it's ready when the top is beautifully golden brown and a toothpick inserted into the center comes out clean.
Let the casserole cool for about 10 minutes before slicing and serving. This allows it to set perfectly. Enjoy your healthy and hearty meal!