To a large skillet with a lid or Dutch oven over medium heat, add olive oil. Once hot and shimmering, add the diced onion and cook for 4 to 5 minutes, stirring occasionally, until softened.
Add the ground beef and cook over medium heat, breaking it apart with a spatula, until fully browned and cooked through, 8 to 10 minutes. Drain any excess grease from the pan.
Stir in the garlic and tomato paste. Cook for 1 minute, until the tomato paste is fully incorporated.
Sprinkle in the taco seasoning, then add the diced tomatoes with green chilies, beef broth, heavy cream, and uncooked pasta.
Stir everything together, making sure the pasta is submerged in the liquid.
Bring the mixture to a low boil, then reduce the heat to a simmer. Cover the pot and cook, stirring occasionally, until the pasta is tender, about 10 to 12 minutes.
Remove the skillet from heat once the pasta is tender and most of the liquid has been absorbed.
Add the cream cheese, cheddar, and Monterey Jack cheeses and stir until fully melted and smooth.
Fold in the sour cream until just combined.
Serve immediately, garnished with cilantro, jalapenos, and sour cream.