Preheat oven to 350 degrees and coat a 1-qt casserole dish with cooking spray. Set aside.

In a large bowl, stir mayo, Monterey Jack cheese, Asiago cheese, finely diced Vidalia onion, Worcestershire sauce and garlic powder together until well combined.

Transfer the mixture to the prepared casserole dish and bake for 45-50 minutes until hot and bubbly.

Remove from oven then cool 10 minutes before serving.