Preheat the oven to 400 degrees F.
Heat a 10-inch oven-safe skillet over medium-low heat and add the butter. Stir in the onions with a pinch of salt and pepper. Cook, stirring often, until the onions caramelized, about 30 minutes. Turn off the heat.
In a large bowl, stir together the eggs, cream, herbs, garlic, mozzarella cheese and caramelized onions. Stir in a pinch of salt and pepper. Whisk until combined. Stir in the potato chips.
Pour the mixture into the same skillet where you caramelized the onions. Stick the skillet in the oven and bake the frittata for 10 to 15 minutes, or until it’s set in the center. You want the eggs set - if they aren’t, bake it for another 2 minutes and check again.
Remove it from the oven and sprinkle with parmesan and extra herbs. Slice it into squares or wedges - whatever you prefer. This tastes great hot or cold! The leftovers from the fridge are great too.