Preheat oven to 425 degrees. Line two baking sheets with parchment paper or silicon baking mats.
Prepare the Macaroni and Cheese according to the package directions omitting the additional milk and butter. Let cool for 10 minutes.
Combine the ground beef with the grated onion and carrot, bread crumbs, salt, and pepper.
Add in the prepared Macaroni and Cheese. Using about ¼ cup per meatball, roll into balls.
Place on prepared baking sheets, spray with cooking spray, and bake for 20 minutes or until they are browned. The meatballs will feel soft; they firm up a little as they cool. Let cool for 5 minutes and serve.