Bring a large pot of salted water to a boil and cook the elbow macaroni according to the package directions. Drain and set aside.
2. Cook the Ground Beef
In a large skillet over medium heat, cook the ground beef until fully browned, breaking it apart as it cooks. Drain any excess fat.
Add the taco seasoning, water, and salsa to the skillet. Stir and let it simmer for about 5 minutes until the mixture thickens slightly. Remove from heat and set aside.
3. Make the Cheese Sauce
In a medium saucepan, melt the butter over medium heat. Stir in the flour and cook for about 1 minute to create a roux.
Slowly whisk in the milk, cooking until the sauce thickens, about 3-4 minutes.
Stir in 1 ½ cups of cheddar cheese and the Monterey Jack cheese, whisking until melted and smooth.
Remove from heat and stir in the sour cream for extra creaminess. Add salt and pepper to taste.
4. Combine Everything
In a large mixing bowl or the same pot you cooked the pasta in, combine the cooked macaroni, taco beef mixture, and cheese sauce. Stir until everything is evenly coated and combined.
5. Top with Cheese
If desired, transfer the mixture to a greased 9×13-inch baking dish. Sprinkle the remaining ½ cup of cheddar cheese on top.
Bake in a preheated oven at 350°F (175°C) for 15-20 minutes until the cheese on top is melted and bubbly.
6. Serve
Serve warm and garnish with optional toppings like cilantro, diced tomatoes, sliced jalapeños, or crushed tortilla chips for added crunch and flavor.
