Step 1: Cook the Macaroni: Cook the elbow macaroni according to package directions. Drain well and set aside.
Step 2: Brown the Ground Beef: In a large skillet, brown the ground beef over medium-high heat. Drain off any excess grease.
Step 3: Saut Aromatics: Add the chopped onion and minced garlic to the skillet with the ground beef. Cook until the onion is softened and translucent, about 3-5 minutes.
Step 4: Season with Taco Seasoning: Stir in the taco seasoning packet and mix well to coat the ground beef evenly.
Step 5: Prepare the Cheese Sauce: In a large saucepan or pot, melt the butter over medium heat. Whisk in the flour and cook for 1-2 minutes, creating a roux.
Step 6: Thicken the Sauce: Gradually whisk in the milk, ensuring there are no lumps. Continue to whisk until the sauce thickens, about 5-7 minutes.
Step 7: Incorporate Cheese and Seasonings: Reduce the heat to low. Add 3 cups of the shredded cheddar cheese, salt, and pepper to the sauce. Stir until the cheese is melted and the sauce is smooth and creamy.
Step 8: Combine Everything: Add the cooked macaroni and the seasoned ground beef mixture to the cheese sauce. Stir well to combine.
Step 9: Garnish and Serve: Transfer the taco mac and cheese to a serving dish or individual bowls. Top with the remaining 1 cup of shredded cheddar cheese and any desired toppings. Serve immediately.
Tips & Substitutions: For a spicier version, add a pinch of cayenne pepper to the cheese sauce or use a spicier taco seasoning. Ground turkey or chicken can be substituted for ground beef. For a creamier sauce, use half-and-half or heavy cream instead of milk. To make it vegetarian, use a plant-based ground meat substitute.