In a large pot, bring salted water to a boil. Add the dry macaroni and cook according to package instructions until al dente. Drain and set aside.
In the same pot, bring a small amount of water to a simmer. Add the thinly sliced cauliflower and a pinch of kosher salt. Steam for about 5-7 minutes until tender.
Transfer the steamed cauliflower to a blender or food processor. Blend until smooth, adding a splash of water if needed to achieve a creamy consistency.
In a large mixing bowl, combine the blended cauliflower, grated Jack cheese, grated Gruyère cheese, and sugar. Stir until well mixed.
Add the cooked macaroni to the cheese and cauliflower mixture. Stir until every piece of pasta is coated in that luscious, creamy sauce.
If you prefer a baked version, preheat your oven to 350°F (180°C). Transfer the mixture to a baking dish and bake for about 20-30 minutes until heated through and bubbly. For an extra crispy top, broil for an additional 2-3 minutes.