Grate the cheeses on the large side of the cheese grater and set some aside for topping.
Preheat the oven to 375° and make sure your cast iron skillet (10-inch) is well seasoned. You can also use a 9-in round, an 8x8, or a 9x9 ceramic or glass baking dishes if you prefer, just make sure to lightly grease it.
In a medium mixing bowl, combine all of the ingredients for the dip and mix very well, until evenly incorporated.
Spread the dip mixture in a baking dish evenly and top off with the cheese that you set aside.
Bake for 17-20 minutes. (You can turn on broil for a few seconds if you want a golden brown top but make sure to keep an eye on it.)