Preheat a 12-inch seasoned cast iron skillet in a 500º F oven for 15-20 minutes.
Roll out room temperature pizza dough big enough to cover the bottom of the skillet, plus about 1 inch of the sides of the skillet -- 14 inches in diameter. The dough circle does not have to be perfectly round.
Beat together the eggs and milk with salt and pepper to taste.
Using pot holders, carefully remove the hot skillet from the oven and set it on a sturdy heat proof surface.
Place the pizza dough in the hot skillet.
Pour the egg and milk mixture onto the dough.
Scatter ¾ of the chopped scallions into the eggs, reserving ¼ for garnish later.
Scatter the chopped bacon on top.
Scatter the cheeses on top.
Bake in the hot oven 10 minutes, until the eggs are set and slightly puffed and the edges of the dough begin to brown.
Using two spatulas, remove the pizza to a cooling rack and sprinkle on the remaining chopped scallions as garnish.
Let cool five minutes, slice and serve.