This taco mac and cheese is pure comfort food with flavorful beef, tender shell pasta and a luscious, cheesy white sauce!
First, get a large pot of water on the stove to boil for the pasta. Salt it liberally. While it comes to a boil, get out a large skillet with deep sides and heat the oil in it over medium high heat. Add the beef, onion, taco seasoning, salt, tomato paste, beer and lime juice. Stir it all together while you brown the beef and break it up. Let it all simmer together to let the liquid cook off and get it to develop flavor for about 6-8 minutes. Remove it to a plate and add the butter to the pan. Let it start to melt and then whisk the flour in. Let the flour and butter cook together and thicken for a couple of minutes until it is a thick paste. Slowly pour in the milk while you keep whisking until it is a smooth white sauce. Let it simmer and thicken for about 10 minutes, whisking it often.
While the sauce cooks, the water should be boiling. Cook the pasta until tender for about 8 minutes, then drain it. When the sauce is done, whisk in the cheese until it is a smooth cheese sauce. Then stir the beef back in and the pasta, tossing it all together thoroughly. Serve it immediately and enjoy!! It also makes fantastic leftovers! Enjoy!!