In a medium bowl, combine ground beef, pesto, egg, breadcrumbs, 1 tsp salt and ¼ tsp pepper. Mix well with clean hands and form in to 8 meatballs.
Add olive oil and ¼ cup of marinara sauce to the bottom of the inner pot and set Instant Pot to Sauté function. Cook meatballs for 2 to 3 minutes. Shake the pot gently to make sure the meatballs aren’t sticking to the bottom.
Press Cancel. Scatter the pasta over the meatballs, layer in opposite directions to prevent the pasta from clumping together. Top pasta with remaining 1 cup of sauce, followed by 2 cups of water.
Cover and lock the lid in place, set to Pressure Cook on high pressure for 9 minutes. When the cook time is up, quick release the pressure. Remove the lid, pour pasta and meatballs out onto a large platter or serving dish. Serve with Parmesan cheese, if desired.
Nutrition Info Per Serving: Serves: 4 (does not include Parmesan cheese) ; Calories: 611 ; Total Fat: 20 grams; Saturated Fat: 6 gram; Total Carbohydrate:72 grams; Sugars: 8 grams; Protein: 37 grams; Sodium: 794 milligrams; Cholesterol: 121 milligrams; Fiber: 3 grams.