Cheesy Taco Pasta

In a large pot of salted boiling water, cook pasta according to package directions until al dente. Drain, reserving 1 cup pasta water, and return to pot. Meanwhile, in a large skillet over medium heat, heat oil. Add onion and season with salt. Cook until tender, 5 minutes, then add jalapeño. Cook 2 minutes more. Add ground beef and cook until no longer pink, 6 minutes, then add taco seasoning. Drain fat. Add canned tomatoes and 1/4 cup reserved pasta water and stir, then add cheese and let melt, stirring occasionally, 2 minutes. Add cooked pasta and toss until completely combined. Garnish with cilantro and serve.