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 and cook, breaking it apart with a spoon, until browned and cooked through, about 7-8 minutes. Drain excess fat if necessary.
Add diced green bell pepper, zucchini, and chopped cauliflower to the skillet. Cook for 5 minutes until vegetables are tender.
Stir in dried Italian seasoning, salt, and black pepper. Remove the skillet from heat.
In a medium bowl, combine sour cream and heavy cream until smooth.
Add the sour cream mixture to the skillet and stir until everything is evenly coated.
Transfer the mixture to a 9×9 inch casserole dish and spread evenly.
Sprinkle shredded cheddar cheese evenly over the top.
Bake in the preheated oven for 20 minutes until cheese is melted and bubbly.
Remove from oven and let cool for 5 minutes before serving.