Brown the Beef: In a large pot or Dutch oven, heat over medium heat and add 1 lb of lean ground beef. Cook for about 5–7 minutes, breaking it up with a spatula, until it’s browned and no longer pink. Stir in ground cumin, dried minced onion, and garlic powder until fragrant, about 30 seconds. Drain any excess fat if necessary.

Create the Sauce: Add 2 tablespoons of tomato paste and ½ cup of diced tomatoes with green chilies into the pot, stirring well to combine. Pour in 1 cup of beef broth and 1 cup of whole milk, then bring the mixture to a gentle boil over medium-high heat.

Cook the Pasta: Once boiling, carefully stir in 8 oz of shell pasta. Reduce the heat to medium-low, cover the pot, and simmer for 8–10 minutes, stirring occasionally.

Melt the Cheese: Lower the heat and stir in 1 cup of Monterey Jack cheese and 1 cup of mild cheddar cheese. Pour in the reserved ½ cup of whole milk. Stir continuously until the cheese melts and forms a thick, creamy sauce, about 2–3 minutes.

Serve and Add Toppings: Once everything is combined and smooth, remove the pot from heat. Serve warm, letting everyone add their favorite toppings.