In a large skillet over medium-high heat, add ground beef and cook until browned and fully cooked, about 5-7 minutes.

Drain any excess fat if necessary, then stir in taco seasoning and water. Let it simmer for about 5 minutes until thickened and fragrant.

While the beef simmers, boil salted water in a separate pot. Cook elbow macaroni according to package instructions until al dente, then drain and set aside.

In the same pot used for the pasta, heat olive oil over medium heat. Add diced tomatoes and cook for 2-3 minutes, stirring occasionally.

Add the drained macaroni back into the pot along with the beef mixture and sautéed tomatoes. Mix everything thoroughly.

Pour in milk and stir until well combined. Gradually mix in shredded cheddar and shredded mozzarella until melted and creamy.

Stir in sour cream until fully incorporated.

Finish off with chopped green onions sprinkled on top before serving.