Brown the meat: Heat a large, deep skillet or Dutch oven over medium-high heat.
Add olive oil if using lean meat. Cook the ground beef, breaking it up with a spoon, until browned and no longer pink, about 5–7 minutes. Drain excess fat if needed.
Sauté the aromatics: Add the diced onion and cook until softened, 3–4 minutes.
Stir in the garlic and cook until fragrant, about 30 seconds.
Season it up: Sprinkle in the taco seasoning and ranch seasoning. Stir to coat the meat and onions so the spices toast briefly.
Add liquids and pasta: Pour in the salsa, the diced tomatoes with their juices, and the broth. Stir well, then add the pasta.
If you’re using corn, black beans, or jalapeño, add them now.
Simmer: Bring to a boil, then reduce to a gentle simmer. Cover and cook, stirring every few minutes so the pasta doesn’t stick, until the pasta is al dente and most of the liquid is absorbed, 12–15 minutes. If it looks too dry before the pasta is done, add a splash more broth or water.
Make it creamy: Reduce the heat to low.
Stir in the cream cheese until smooth and melted. Fold in the shredded cheese until the sauce is thick and glossy. Taste and adjust salt and pepper.
Finish and serve: Let it sit off the heat for 2–3 minutes to thicken.
Top with green onions, cilantro, avocado, a dollop of sour cream, and a squeeze of lime, if you like. Serve warm.