In a large bowl, combine ground chicken, breadcrumbs, egg, 2 cloves minced garlic, salt, and pepper. Scoop mixture into 1-in meatballs and place on a plate.
Heat an instant pot using BROWN/SAUTE function. Melt butter and oil and swirl to coat bottom of instant pot. Place meatballs in instant pot and sear on all sides until lightly browned. Transfer to a plate.
Keep instant pot on. Sauté onion in instant pot drippings until tender. Add garlic, ginger, garam masala, coriander, turmeric, and tomato paste to instant pot and cook 2-3 minutes until fragrant.
Stir chicken broth into tomato paste until smooth. Add meatballs to instant pot, lock lid into place, and close vent. Cook meatballs on high pressure 8 minutes, then allow to release steam naturally 10 minutes.
Release any remaining steam from instant pot and unlock lid. Fold heavy cream into sauce until smooth and season sauce with salt and pepper to taste if needed. Serve meatballs and sauce warm over rice with fresh cilantro and naan.