Position oven rack to highest position beneath heating element.
Set oven temperature to broil.
Wash peppers under cold running water and pat dry with paper towels.
Place peppers on a cookie sheet.
Place in the oven under the broiler and roast for 10-15 minutes or until skin is charred and blistered.
Flip peppers over and roast for another 10-15 minutes or until skin on the second side is charred and blistered.
Remove peppers from oven. See tongs to transfer peppers into a paper bag.
Seal the bag and leave peppers to steam for 10 minutes.
Remove peppers and peel off the charred papery outer skin and discard.
Slice open peppers and remove seeds and discard stems. Set aside.
Reposition oven rack to center of the oven and preheat to 350℉.
Arrange half the Poblano peppers in the bottom the casserole dish.
Top with ½ the shredded Pepper Jack cheese and ½ the shredded Cheddar cheese.
Repeat layers using up the remaining Poblano peppers and shredded cheeses.
In a mixing bowl, whisk together milk, eggs, flour, baking powder, onion powder, garlic powder, salt and pepper.
Pour the mixture evenly over the cheese and peppers in the casserole dish.
Baker for 45 minutes until golden brown along the edges and center no longer jiggles when dish is shaken.
Cool for 10 minutes before slicing.
Serve topped with sour cream, salsa and garnish with fresh cilantro.