Preheat oven to 400 degrees F. Spray 13x9 baking dish with cooking spray.
2
Heat large skillet over medium-high heat and spray bottom with cooking spray. Add onion and garlic and saute 1 minute.
4
Remove from heat, add chicken and 1 cup cheese. Stir to combine.
5
Spread uncooked borsetti pasta evenly in bottom of baking dish. Top with chicken and vegetable mixture, making sure all pasta is covered. Sprinkle remaining cheese over the top.
6
Bake uncovered for 20 minutes on center oven rack until heated through and cheese is melted and bubbly. Let stand 5 minutes before serving.