01 - Bring a large pot of water to a boil. Add cauliflower florets and cook for 8 minutes or until very tender. Drain well.
02 - In a blender, combine cooked cauliflower, whole milk, ground mustard, garlic powder, salt, and black pepper. Blend until completely smooth.
03 - Bring a large saucepan of salted water to a boil. Add elbow macaroni and cook according to package instructions until al dente. Drain well.
04 - Return drained macaroni to the pot. Pour in blended cauliflower mixture and set over low heat. Stir in shredded cheddar and grated parmesan, mixing until cheese is fully melted and sauce coats the pasta.
05 - Divide macaroni with sauce among plates and serve immediately, garnishing with additional black pepper if desired.