Creamy Baked Double Cheese and Onion Dip (gluten-free)

cream cheese, softened (light is okay, I used TJ’s Soft Spreadable Light

mayonnaise (light is okay, I used Best Foods Light Mayo)

to 8 ounces grated cheese, divided (I used 7-ounces Blarney Castle Gouda, use your favorite cheese)

medium/large sweet Vidalia onion, peeled and diced (about 1 heaping cup)

ground black pepper, or to taste

salt, or to taste

cayenne pepper, optional and to taste