Cook the macaroni according to the package directions. Drain well and set aside.
While the pasta cooks, cut the cauliflower into small pieces.
Steam for about 10 minutes, or until the cauliflower is very soft and can easily be pierced with a fork.
Add the steamed cauliflower to a blender along with the milk, shredded cheddar cheese, butter, and salt.
Blend until the mixture is completely smooth and creamy.
Pour the cauliflower cheese sauce over the macaroni while the pasta is still warm.
Stir until all of the noodles are evenly coated.
Serve the mac and cheese immediately, or divide it into silicone cupcake liners for meal prep.
Store refrigerated portions for up to 5 days.
To freeze, place the filled silicone cups on a sheet pan and freeze until solid. Transfer the frozen portions to a freezer-safe bag or container and store for up to 3 months.