Preheat the oven to 350°F.
In a medium mixing bowl, combine cream cheese, mayonnaise, sour cream, onion powder, garlic powder, and diced jalapeños. Use a hand mixer for quick blending.
Add 1 cup each of cheddar and jack cheeses and stir to combine.
In a large mixing bowl, toss together pasta, chicken, and most of the bacon, reserving about ½ cup to sprinkle over the top.
Add the cream cheese mixture to the pasta mixture and stir gently until the mixture is evenly combined.
Spread filling into a 9x13-inch casserole dish.
Top with remaining cheeses. Sprinkle reserved bacon and fresh jalapeño slices over the cheese.
Bake for 20 minutes, until the cheese is melted. Remove from the oven and top with freshly sliced green onion. Serve hot.