Set a 6-qt Instant Pot to the high saute setting. Melt butter; add onion, carrot and celery, and cook, stirring often, until onions have become translucent, about 3-4 minutes.
Add ground beef, pork, pancetta, 1 teaspoon salt and 1/2 teaspoon pepper, and cook until browned, about 5-10 minutes, making sure to crumble the beef and pork as it cooks; drain excess fat.
Stir in tomato paste, garlic, oregano, red pepper flakes, nutmeg and cinnamon until fragrant, about 1 minute.
Stir in wine, scraping any browned bits from the bottom of the pot, and cook until reduced, about 2 minutes.
Stir in crushed tomatoes and beef stock. Select manual setting; adjust pressure to high, and set time for 20 minutes. When finished cooking, quick-release pressure according to manufacturer's directions.
Select low saute setting; simmer, uncovered, stirring often, until thickened to desired consistency, about 5-10 minutes. Stir in heavy cream and parsley; season with salt and pepper, to taste.