In a spacious skillet, cook the beef over medium heat until it's browned and devoid of any pink hue. Drain the excess fat.

Stir in the cream cheese, salt, and chili powder. Let the mixture simmer for about 5 minutes, allowing the flavors to meld.

While the beef mixture is simmering, boil a pot of lightly salted water. Add the pasta shells and cook until they're perfectly al dente, which should take around 8 to 10 minutes. Once done, drain and toss the shells in the melted butter.

Preheat your oven to a cozy 350 degrees F (175 degrees C).

Stuff each pasta shell with the beef mixture and place them in a 9x13-inch baking dish. Drizzle the taco sauce over the shells.

Cover the dish with foil and bake for 15 minutes in your preheated oven.

After the initial baking, sprinkle the Cheddar cheese, Monterey Jack cheese, and crushed tortilla chips over the shells. Return to the oven for an additional 15 minutes.

Once baked to perfection, top with dollops of sour cream and serve hot!