Preheat the oven to 375° F and coat a 9×13 baking dish with butter or non-stick spray. Set aside.
Bring a large pot of water to a rolling boil. Add cauliflower florets to water and blanch for 3-5 minutes. Drain cauliflower and set aside.
Heat a large skillet under medium heat.
Add olive oil and onion to the pan and saute for 4-6 minutes until tender. Add garlic and cook for an additional 1-2 minutes.
Add ground meat to pan along with salt, pepper, Italian seasoning, and oregano to make your meat sauce. Cook until browned. Stir in tomato paste and cook for an additional 1-2 minutes.
Stir in crushed tomatoes and let simmer for 5-7 minutes. Adjust seasoning to taste. Remove from heat.
Add blanched cauliflower florets to the prepared baking dish. Pour meat sauce over cauliflower.
Top with ricotta cheese, parmesan, and mozzarella.
Bake for 25-30 minutes until top is bubbling and cauliflower is tender.