I tried cast iron pizza not too long ago, and I also struggled to get it crispy. I tried preheating the cast iron before adding the dough. I think when I try it again next that I will bake the crust without toppings for a bit. I usually pre-bake my crusts for about 5–7 minutes before topping, so not sure why I didn't do that in the deep dish cast iron.

That looks yummy!