Heat oven to 350°F and spray a 2-quart casserole dish with cooking spray.
Cook pasta to al denté (per package directions), drain, and rinse with cool water. Lay the shells, open-side down, on a paper, to allow to dry while preparing the other ingredients.
Heat a large skillet over medium heat. Add the oil, onion and diced jalapeno. Cook the onion and jalapeno, stirring occasionally, until translucent and fragrant, about 4-5 minutes. Transfer the cooked vegetables to a paper towel.
Add the ground beef to the skillet and cook, breaking the beef apart, until lightly browned. If there is just a small amount of rendered fat in the pan, no need to drain.
Add taco seasoning, cream cheese, salt, black pepper, ¼ cup taco sauce and ½ cup shredded cheese to the beef mixture and stir well.
Cook 2-3 minutes, over medium-low heat, until mixture is hot and cheese has melted. Remove from heat.
Pour ¼ cup taco sauce into the prepared casserole dish.
Fill each pasta shell with 2 tablespoons beef/cheese mixture and place the shells into the prepared dish on top of the sauce.
Pour the remaining ¾ cup taco sauce around and in-between the shells.
Cover and bake 20 minutes.
Remove the dish from the oven, uncover, and sprinkle with crushed corn chips. Sprinkle the remaining cheese on top and bake about 10-15 minutes or until the cheese melts.
Garnish with sour cream, chopped cilantro and sliced green onions.