INSTRUCTIONS
1. Preheat the oven to 400 °F . Grease 2 standard 12-cup muffin tins.
2. Bring a large pot of salted water to a boil. Stir in macaroni and boil 5 minutes; drain and return to the pot. Stir in cheese packet, milk, and butter until well combined and creamy. Set aside and keep warm.
3. Heat a large nonstick skillet over medium-high heat. Add beef and cook, stirring often and breaking up with a spatula, until browned and crumbly, about 5 minutes. Add taco seasoning and onion and cook for 2 minutes, stirring constantly. Add water and cook, scraping up any browned bits from the bottom of the pan. Stir in tomatoes and remove from heat.
4. Stir beef mixture into prepared macaroni and cheese. Season to taste with additional taco seasoning. Stir in cheese. Scoop mixture into prepared muffin pans. Use a small spoon to create a small well in the center for toppings later. Alternatively, mixture can be placed in a lightly greased casserole dish and baked as a side dish.
5. Bake in the preheated oven until browned around the edges and bubbly, 20 to 25 minutes. Let stand for 10 minutes. Serve with desired toppings.
