Adjust the oven rack to upper-middle position and preheat oven to 400° F.

In a 10-inch oven proof skillet over medium heat. Add the pancetta, and cook stirring occasionally until golden and crispy. With a slotted spoon, remove the pancetta and place onto a paper towel lined plate. Add the chopped onion to the skillet and cook, stirring occasionally, until tender, about 4-5 minutes.

Meanwhile, lightly beat the eggs with the heavy cream, parsley, sea salt and pepper to taste.

Add the pancetta back to the skillet, stir in the peas, then spread the ingredients out evenly in the pan with a spatula. Pour the egg mixture over it and without stirring, cook until the edges have started to set, between 1-3 minutes. Transfer the pan to the oven and bake until the center has just set, about 10-12 minutes.

If using a non-stick skillet, slide or invert gently onto a large plate, let cool for a few minutes, then serve. If using cast iron, just cut and serve slices directly from the pan.