Preheat the oven to 350°F (175°C).
In a large bowl, combine the 2 tablespoons melted butter, ground turkey, bread crumbs, diced onion, 1/4 cup chopped parsley, grated Parmesan, eggs, pressed garlic (1 clove), Italian seasoning, salt, and pepper; mix with clean hands until evenly combined.
Form the mixture into 2-inch meatballs, arranging them on a plate as you go.
Heat 1 tablespoon olive oil in a large oven-safe skillet over medium heat. Add the meatballs and brown on all sides, turning every 1–2 minutes until nicely seared (about 4–6 minutes total). Remove the meatballs and set aside.
Add the lemon juice to the skillet and scrape up any browned bits to deglaze the pan. Then add 6 tablespoons butter and 2 pressed garlic cloves; cook and stir until the butter is melted and the garlic is fragrant, about 3–4 minutes. Stir in 2 tablespoons chopped parsley.
Return the meatballs to the skillet and turn them to coat in the garlic butter sauce. Transfer the skillet to the preheated oven and bake until the meatballs reach 165°F (74°C), about 10–15 minutes.
If you don't have an oven-safe skillet, transfer the meatballs and sauce to a baking dish and bake for 15–20 minutes until cooked through.