Boil your pasta in salted water according to package directions until a dente. (It will cook a little bit more in the sauce at the end.)
Peel and dice an onion into small pieces. Sauté it in a large skillet with 2 tablespoons of olive oil and 1/2 teaspoon of salt over low heat for 5 minutes.
Add minced garlic and sauté for another minute, then add the fresh or frozen peas to the onions and garlic and turn the heat to medium.
Scoop out 1 cup of pasta cooking water and add it to the skillet with the peas with 4 tablespoons of butter and simmer for about 5 more minutes until the butter is melted and the peas are tender.
Add 3/4 cup of vegan parm (saving 1/4 cup for garnishing) and give it a good stir and allow the cheese to melt.
Drain the cooked pasta, then add it to the cooked peas. Stir well and add salt and pepper to taste and a few shakes of red pepper flakes if desired. Allow it to sit for a few minutes to soak up the flavors of the sauce.
Sprinkle with fresh chopped parsley and the remaining 1/4 cup of vegan parm.
Notes
Saute the onion over low heat to bring more sweetness and flavor.
To make this a creamy pea pasta sauce - Transfer the cooked onion and pea mixture to a blender and puree it until smooth before mixing it with the pasta. This is great for kids and picky eaters.
Don't want to use butter? You can swap it out for 1/2 cup of cashew cream or coconut cream.