Cook the pasta shells according to package instructions until al dente in a pot with salted water. Reserve one cup of the cooking water to thin out the sauce. Drain, return to the pot, and keep warm.

In a medium-sized skillet, brown the ground beef with the onion, garlic, and jalapeno until no longer pink.

Pour in the fire-roasted diced tomatoes, the reserved cup of pasta cooking water, tomato paste, and taco seasoning. Cook for about three minutes.

Sprinkle one cup of shredded cheddar into the sauce and stir until melted. Adjust seasoning with salt and pepper.

Mix the sauce into the pot with the cooked pasta and stir in the reserved half cup of cheddar. Serve with chopped cilantro on top.