In a large bowl, combine Meatball Mixture ingredients thoroughly and form into 30 meatballs.
Add olive oil and 2 tbsp butter to the Instant Pot. Using the display panel select the SAUTE function.
When oil gets hot and butter melts, brown the meatballs. Meat will not be cooked through. Do not crowd the pot–you will have to work in batches. Transfer browned meat to a shallow dish and cover loosely with foil.
Add broth to the pot and deglaze by using a wooden spoon to scrape the brown bits from the bottom of the pot.
Add remaining Sauce Mixture ingredients to the pot and stir until well combined.
Put the meatballs back into to the pot, ensuring all are coated in sauce.
Turn the pot off by selecting CANCEL, then secure the lid, making sure the vent is closed.
Using the display panel select the MANUAL or PRESSURE COOK function*. Use the +/- keys and program the Instant Pot for 3 minutes.
When the time is up, let the pressure naturally release for 7 minutes, then quick-release the remaining pressure.
Carefully remove the meatballs from the pot to a shallow dish and cover loosely with foil.
In a small bowl whisk together the remaining 1/2 cup cream and flour. Stir into the pot and simmer 3-5 minutes until thickened, returning to SAUTE mode as needed. Adjust seasonings.
Serve sauce-coated meatballs as an appetizer, or as an entree over egg noodles, mashed potatoes or rice. Garnish with additional chopped parsley.
*The MANUAL and PRESSURE COOK buttons are interchangeable.