Preheat oven to 350°F; spray a 9x13-inch dish.
Cook beef and onion in large skillet over medium-high about 8 minutes until beef is browned and onion softened. Drain fat; add taco seasoning according to package.
Mix cream cheese, sour cream, and chiles in medium bowl until smooth and combined.
Spread 1/2 cup sauce in dish; cover with 4 tortillas, overlapping as needed.
Spread half the beef over tortillas; dollop and gently spread half the cream cheese mixture. Top with half the beans and 1 cup cheese.
Pour 3/4 cup sauce over cheese; layer 4 tortillas, remaining beef, remaining cream cheese mixture, remaining beans, and 1 cup cheese.
Top with final 4 tortillas, remaining sauce, and remaining 1 cup cheese.
Cover with foil; bake 25 minutes, then uncover and bake 10 minutes until cheese is bubbly and golden.
Rest 10 minutes before cutting squares; garnish with optional cilantro and serve warm.