Preheat oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish.
Cook macaroni according to package instructions until just al dente. Drain and set aside.
Steam cauliflower until very tender, about 8–10 minutes. Blend until smooth and creamy.
In a saucepan over medium heat, warm olive oil. Whisk in flour and cook for 1 minute.
Slowly whisk in milk and cook until slightly thickened, about 3–4 minutes.
Stir in cauliflower puree, cheddar cheese, cream cheese, garlic powder, onion powder, salt, and pepper. Mix until smooth.
Combine cooked pasta with cheese sauce and stir until evenly coated.
Transfer to prepared baking dish.
Mix breadcrumbs with Parmesan and sprinkle evenly over the top.
Bake uncovered for 25–30 minutes, until bubbly and lightly golden.
