I always place the muffin tin on a rimmed baking sheet just in case of spillage! Bake for about 18-20 minutes. They should puff up a bit and be fully set in the center. I let them sit for about 3-5 minutes after taking them out of the oven to rest and firm up a bit. If needed, you can loosen by running a knife around the edges of each frittata to loosen them from the pan. Using Pam, I find I never need that step.
Other filling options:
I like to have some fresh and warm from the oven, with extras to put away for future use. Once they've cooled, you can pack them in freezer bags or containers.
You can wrap them individually if you'd like, but I've never had them stick together. Store in the fridge for a few days or in the freezer for a month or two. I like to eat them hot or cold!