Start by taking a large mixing bowl and combining ground chicken, chopped onion, minced garlic, breadcrumbs, egg, salt, black pepper, paprika, and cayenne pepper. Thoroughly mix the ingredients until they are evenly blended.

Shape the mixture into small meatballs, approximately 1 inch in diameter, and arrange them on a tray or plate.

In a large skillet, warm up olive oil over medium-high heat. Add the meatballs and cook them, turning occasionally, until they become browned and fully cooked, which usually takes about 8-10 minutes. Afterwards, transfer the cooked meatballs to a plate and set them aside.

In the same skillet, melt the butter over low heat. Once it's melted, introduce the hot sauce and stir it in to create a well-blended sauce. You can adjust the amount of hot sauce to achieve your preferred level of spiciness.

Return the cooked meatballs into the skillet along with the buffalo sauce. Gently coat the meatballs with the sauce until they are evenly covered. Allow them to simmer for a couple of minutes to ensure they are heated through.

Serve the Buffalo Chicken Meatballs while they're hot, and if you like, garnish them with fresh parsley. They make an excellent choice as an appetizer or a main course.