Preheat the oven to 375°F (190°C).
Heat the olive oil in a large skillet over medium heat.
Add the diced onion and cook for 3-4 minutes until softened.
Add the minced garlic and cook for 1 minute until fragrant.
Add the ground beef to the skillet and cook, breaking it apart with a spatula, until browned and cooked through, about 7-8 minutes.
Drain any excess fat from the skillet.
Add the diced green bell pepper, zucchini, mushrooms, and cauliflower to the skillet. Cook for 5-6 minutes until the vegetables are slightly tender.
Stir in the dried oregano, dried basil, salt, and black pepper.
In a separate bowl, combine the heavy cream, sour cream, shredded cheddar cheese, and grated Parmesan cheese. Mix well.
Pour the cheese and cream mixture into the skillet with the beef and vegetables. Stir to combine evenly.
Transfer the mixture to a 9×9-inch (23×23 cm) casserole dish and spread it out evenly.
Bake in the preheated oven for 25-30 minutes, or until the casserole is bubbly and the top is golden brown.
Remove from the oven and let it cool for 5 minutes before serving.