1. Heat a large deep skillet or Dutch oven over medium-high heat and add the olive oil. Stir in the diced onion and cook for 3–4 minutes until softened and translucent.

2. Add the ground beef to the pan and cook, breaking it up with a spatula, until browned and no pink remains. Drain off excess grease if needed and return the pan to the heat.

3. Sprinkle the taco seasoning, salt, and black pepper over the beef and onions. Stir well so the meat is evenly coated and cook for 1 minute to toast the spices.

4. Add the minced garlic and cook just until fragrant, about 30 seconds, stirring constantly so it doesn’t burn.

5. Pour in the diced tomatoes with green chiles (including their juices), the tomato sauce, and the beef broth. Stir, scraping up any browned bits from the bottom of the pan.

6. Stir in the dry pasta shells, pressing them down so they are mostly submerged in the liquid. Bring the mixture to a gentle boil, then reduce the heat to medium-low so it simmers steadily.

7. Cover the pan and cook for 12–15 minutes, stirring every few minutes, until the pasta shells are tender but still slightly firm and the sauce has thickened.

8. Reduce the heat to low and stir in the heavy cream or half-and-half until the sauce looks creamy and silky.

9. Add 1 1/2 cups of the shredded cheese to the pasta and stir until melted throughout. Sprinkle the remaining 1/2 cup cheese over the top, cover the pan again, and let it sit for 2–3 minutes to melt into a cheesy layer.

10. Turn off the heat, taste, and adjust seasoning with more salt or pepper if needed. Garnish with cilantro or green onions and add sour cream, jalapeños, avocado, or crushed tortilla chips if desired. Serve hot straight from the pot.