Steam the peas until they are tender (about 5 minutes). Set aside to cool. In a blender or food processor, blend, 1 1/2 cups of the cooked and cooled peas, egg, egg yolk, cheese and half & half until smooth. Season with salt and pepper.

In a large skillet over medium high heat, cook pancetta or bacon until browned (about 6-8 minutes). If using bacon, cook slightly longer and drain excess fat. Add onions and cook until soft, another 5 minutes.

Cook pasta according to package instructions until tender but still firm to the bite. Drain, reserving 1/2 cup pasta liquid. Add pasta and extra peas (1/2 cup) to the skillet with onions and pancetta and toss. Remove skillet from heat and add pea sauce. Toss quickly to avoid the eggs from scrambling. Add the reserved pasta water as needed to thin out the sauce (I use all of the 1/2 cup).

Transfer to serving bowls and top with extra Parmesan.