Prep the oven and pan: Preheat your oven to 375°F (190°C).
Grease a 9x13-inch baking dish with butter or olive oil.
Cook the bacon: In a large skillet over medium heat, cook the chopped bacon until crisp. Remove with a slotted spoon and set aside. Leave 1–2 tablespoons of bacon fat in the skillet.
Sauté the cabbage: Add the chopped cabbage to the skillet with a pinch of salt and pepper.
Cook, stirring often, for 8–10 minutes until it softens and reduces in volume. If the pan looks dry, add a little butter. Transfer the cabbage to the prepared baking dish and spread it in an even layer.
Brown the beef: In the same skillet, add the ground beef and diced onion.
Season with salt, black pepper, smoked paprika, onion powder, thyme, and red pepper flakes. Cook until the beef is browned and the onion is soft, 6–8 minutes. Stir in the minced garlic and cook 1 minute more.
Drain excess fat if needed.
Make the creamy sauce: Reduce heat to low. Stir the heavy cream and cream cheese into the beef mixture. Simmer gently, stirring, until the cream cheese melts and the sauce thickens slightly, 2–3 minutes.
Taste and adjust salt and pepper.
Assemble: Sprinkle half the cheddar over the cabbage. Spoon the creamy beef mixture evenly over the top. Add the mozzarella and remaining cheddar, then scatter the cooked bacon across the surface.
Bake: Place in the oven and bake for 18–22 minutes, until the casserole is bubbling and the cheese is melted with golden spots.
Finish and serve: Let rest for 5–10 minutes so it sets.
Garnish with parsley or chives and green onions. Scoop and serve hot.