Preheat the oven to 375°F (190°C).
Heat olive oil in a large skillet over medium heat.
Add diced onion and cook for 3-4 minutes until softened.
Add minced garlic and cook for 1 minute until fragrant.
Add ground beef to the skillet, breaking it apart with a spatula, and cook until browned and no longer pink, about 7-8 minutes.
Drain any excess fat from the skillet.
Add diced green bell pepper, zucchini, and chopped cauliflower to the skillet. Cook for 5 minutes until vegetables are slightly tender.
Stir in dried oregano, dried basil, smoked paprika, salt, and black pepper. Mix well.
In a separate bowl, whisk together heavy cream and sour cream until smooth.
Pour the cream mixture into the skillet and stir to combine all ingredients evenly.
Remove the skillet from heat and transfer the mixture into a 9×9 inch casserole dish.
Sprinkle shredded cheddar cheese evenly over the top, followed by grated Parmesan cheese.
Bake uncovered in the preheated oven for 25-30 minutes until the cheese is melted and bubbly and the casserole is heated through.
Remove from oven and let cool for 5 minutes before serving.