Bring a large pot of water to a boil. Add 3 cups uncooked pasta (Radiatore, shells, bowtie, etc.) and cook according to package directions until al dente. Drain and set aside.

Meanwhile, heat a large skillet over medium-high heat. Add 1 lb ground beef, 1 medium red bell pepper (diced), and ½ medium onion (diced). Cook, breaking up the beef, until the beef is no longer pink and the vegetables are softened, about 6–8 minutes. Drain and discard any excess fat.

Reduce heat to medium. Add 2 tsp garlic (minced), ¼ cup Taco Seasoning, and ½ tsp salt to the skillet; stir for about 30 seconds until fragrant.

Add 3 tbsp butter to the skillet and stir until melted and fully incorporated into the beef mixture.

Sprinkle ¼ cup all-purpose flour evenly over the beef mixture and stir to combine. Cook 1–2 minutes, stirring, to remove the raw flour taste.

Gradually add 2 cups beef broth (low sodium) to the skillet, about ½ cup at a time, stirring or whisking after each addition and scraping any browned bits from the bottom of the pan. Bring the mixture to a simmer.

Stir in 2 tbsp tomato paste until fully incorporated. Simmer 2–3 minutes, stirring occasionally, until the sauce thickens slightly.

Reduce heat to low. Stir in ½ cup sour cream and 1 cup Mexican 3 cheese blend (shredded) until the sauce is smooth and the cheese is melted.

Add the cooked pasta to the skillet and stir gently until the pasta is evenly coated with the creamy sauce and heated through, about 1–2 minutes.

Serve immediately.