- Preheat oven to 325 degrees and prepare a 9-inch pie dish with cooking spray.
- In a mixer on medium speed, combine the cream cheese, parmesan cheese, and mayonnaise until just blended. Stir in onions by hand. Scoop into prepared pie dish.
- Bake for 15 to 20 minutes, or until bubbly and browned on top. Serve hot.