* Shown is a combination of 1 cup chopped red bell pepper, ¾ cup shredded zucchini (squeezed with a paper towel to remove excess water), ¼ cup frozen corn, and 1 cup frozen broccoli, which I allowed to thaw slightly before roughly chopping and adding to the pan with the other veggies.
** Because this recipe yields exactly 14 mini frittatas, I use a 12 cup muffin tin and a 6 cup muffin tin to hold the 2 extra frittatas. Both fit on one rack in my oven at the same time.
You could also try using cupcake liners in your muffin tins, but I would use the parchment paper cupcake liners if you can find them. The frittatas might stick to a standard paper liner.