In a large bowl, combine ground chicken, breadcrumbs, egg, Parmesan, garlic, parsley, Italian seasoning, onion powder, salt, and pepper. Mix gently with your hands just until everything comes together. Avoid overmixing.

Shape mixture into tablespoon-sized balls, about 30 total. Refrigerate for 30 minutes before cooking for best shape and juiciness.

Melt butter in a large skillet over medium-high heat. Add meatballs with 1 inch of space between each, working in batches if needed. Brown on all sides, about 6 to 8 minutes total. Transfer to a plate, cover loosely, and set aside. Drain fat and wipe the skillet clean.

Return clean skillet to medium heat. Add the reserved tablespoon of sun-dried tomato oil. Once shimmering, add garlic and cook for 30 seconds until fragrant. Add tomato paste and cook for 1 minute, stirring constantly.

Pour in the chicken stock and deglaze the pan, scraping up any browned bits from the bottom with a wooden spoon.

Reduce heat to medium-low. Add heavy cream, Parmesan, Italian seasoning, and red pepper flakes if using. Simmer for 3 to 4 minutes until the cheese is fully incorporated. Return meatballs to the pan along with the sun-dried tomatoes. Simmer for 10 to 15 minutes until sauce is thickened and meatballs reach an internal temperature of 165 F.

Garnish with fresh basil and season with salt and pepper to taste. Serve immediately.