In a skillet, melt the butter and olive oil over medium heat. Add the chopped onion and sauté for about 5 minutes or until translucent and fragrant.
In a large mixing bowl, combine the ground chicken, sautéed onions, breadcrumbs, milk, egg, chopped parsley, minced garlic, salt, and pepper. Mix gently until just combined.
Using your hands, form the mixture into meatballs roughly 1-2 inches in diameter and place them on a baking sheet or plate.
In a large skillet, heat about 1/4 inch of vegetable oil over medium-high heat.
Carefully add the meatballs to the hot oil, frying them in batches until they are golden brown on all sides and cooked through (about 8-10 minutes).
Transfer the cooked meatballs to a pot with marinara sauce and allow them to simmer for about 10 minutes.
Serve the meatballs hot over spaghetti, in a sub, or on their own with crusty bread. Enjoy!
