What size skillet are you using? I would like to use my 12-inch cast iron skillet, so could I double the ingredients?

if this is any help for you, while waiting for the recipe author:

12" lodge cast iron fry pan with 2" depth holds 12 cups by volume
8" or 9" standard pie plate holds about 4 cups
9 or 10" deep dish (2") pie plate holds about 8 cups each
When I the 12" pan for standard pumpkin pie recipe, it will hold the volume of TWO 10" pies (or one 6-cups volume pumpkin streusel pie, from the recipe here at food52, with plenty of air space at top so not to overflow, can add whipped cream or ice cream when serving, etc).

So, guess is that your 12" will, yes, hold the contents of a doubled zucchini frittat by Renee Kemps. To be safe, make the filling in a measuring container large enough to see its volume before you pour into pie plate.

Remember to adjust (increase) cooking time and check at regular intervals to test doneness.

Good luck, and hope it comes out beautifully!