Preheat oven to 400 F. Lightly grease an 8x8-inch baking dish with non-stick cooking spray.
In a skillet, brown the ground beef with the minced onion and garlic powder. Drain.
Add both cauliflower to the baking dish and gently toss. Add the browned ground beef in with the cauliflower and toss gently to combine.
In a small bowl, whisk together the cream of mushroom soup and the heavy cream. Then pour over the top. Toss gently, if needed. Top with shredded cheese.
Bake in the preheated oven for 30 minutes, or until cheese has melted and begins to golden.
Serve Keto "Hashbrown" Beef Bake with favorite keto sides such as sauteed spinach or steamed broccoli.