Preheat the oven to 350°F and prepare a 9x13 casserole dish by greasing it with nonstick cooking spray.
Prepare and drain the broccoli florets. Spread the cooked broccoli in an even layer in the dish.
In a large saucepan, heat the milk, heavy cream, Velveeta, garlic powder, onion powder, black pepper, and ½ teaspoon Italian seasoning over medium heat. Cook until the cheese is fully melted, stirring constantly.
Remove the pan from heat and stir in the sharp cheddar cheese until melted.
Pour the cheese sauce over the top of the broccoli in the pan. Bake in the preheated oven for 20 minutes.
While the casserole is cooking, combine the crushed Ritz crackers, butter, and remaining Italian seasoning. Stir until well mixed.
Remove the casserole from the oven and top with cracker mixture. Return to oven and bake for an additional 10 minutes, until crackers are browned.