Preheat the oven to 350 degrees.
Place the ground beef and onion in an oven safe skillet over medium high heat on the stove. Saute until the meat is browned and the onions have softened.
Add the taco seasoning, green chilis and cream cheese to the skillet, and saute until the cream cheese is completely melted and combined.
Top the mixture with the corn chips and then the shredded cheese.
Bake for 20 minutes.
Remove the skillet from the oven and top with shredded lettuce and tomato.
Garnish with salsa and sour cream if desired.