Heat oven to 350ºF. Melt butter in a small skillet over medium-high heat. Add onion and garlic; cook 5 minutes, stirring occasionally. Transfer mixture to a large bowl; cool 5 minutes.
Add ground turkey, breadcrumbs, egg, ¼ cup ketchup, Worcestershire sauce, pepper and salt, if desired to turkey mixture; mix well. Press into 8 x 4-inch loaf pan. Spread remaining ½ cup ketchup over top.
Bake 1 hour or until the internal temperature of meatloaf is well-done, 165ºF. as measured by a meat thermometer. Let stand at room temperature 5 minutes before slicing.