Turn on oven broiler
Combine chickpea flour, tapioca starch, herbs, salt, and pepper in a medium bowl. Whisk to combine
Add water and 1 tbsp (14g) olive oil; whisk until smooth. Add grated Parmesan and stir to combine
Place a 10 inch cast iron skillet over medium-high heat. Add remaining 2 tbsp (28g) olive oil. Heat until oil is rippling
Pour in batter and shake and spread into an even layer. Cover the pan (I usually use a baking tray) and cook until the pizza is set in the center and browned underneath, about 5 minutes. Turn off fire
Add toppings (sauce, cheese, etc.) and place cast iron in oven under broiler until everything is melted and bubbly, about 3 minutes
Remove from oven and remove pizza from pan. Allow to cool for a minute or two, then cut and serve