Prepare the Meatballs : In a large bowl, combine the ground chicken, breadcrumbs, Parmesan cheese, egg, minced garlic, parsley, salt, and pepper. Mix gently until all ingredients are well incorporated. Roll the mixture into 1 1/2-inch meatballs and place them on a plate or baking sheet.

Cook the Meatballs : Heat the olive oil in a large skillet over medium heat. Add the meatballs in batches, being careful not to overcrowd the pan. Cook for 3-4 minutes on each side, until golden brown and cooked through. Transfer the cooked meatballs to a plate and set aside.

Make the Sauce : In the same skillet, melt the butter with the olive oil over medium heat. Add the minced garlic and sauté for about 1 minute, until fragrant. Stir in the chicken broth, lemon juice, and capers. Bring the mixture to a gentle simmer and cook for 3-4 minutes, allowing the flavors to meld. If you prefer a creamy sauce, stir in the heavy cream and cook for an additional 2 minutes, until slightly thickened. Season with salt and black pepper to taste.

Combine and Serve : Return the meatballs to the skillet, spooning the sauce over them to coat. Let the meatballs simmer in the sauce for 2-3 minutes to warm through. Garnish with chopped parsley and lemon slices, if desired. Serve hot over pasta, rice, or with crusty bread for dipping.