Preheat the Oven: Begin by preheating your oven to 400°F (200°C).
Prepare the Vegetables: Wash and cut the cauliflower and broccoli into bite-sized florets.
In a large mixing bowl, toss the cauliflower and broccoli florets with olive oil, salt, black pepper, garlic powder, and onion powder.
Roast the Vegetables: Spread the seasoned vegetables in a single layer on a large baking sheet and roast for 20-25 minutes.
Prepare the Creamy Sauce: In a medium saucepan over low heat, combine cream cheese and heavy cream until smooth, then add shredded cheddar cheese and stir until melted.
Stir in dried thyme and dried basil, adjusting seasoning as needed.
Combine Vegetables and Sauce: In a large mixing bowl, combine the roasted vegetables with the creamy cheese sauce.
Transfer to Baking Dish: Grease a 9×13-inch baking dish and pour the vegetable and sauce mixture into it.
Add Toppings: Sprinkle grated Parmesan cheese over the top of the casserole.
Bake the Casserole: Bake for 20-25 minutes until the top is golden brown and bubbly.
Cool and Garnish: Let the casserole cool for 5-10 minutes, then garnish with chopped parsley and crushed red pepper flakes.
Serve and Enjoy: Cut the casserole into squares and serve warm.
