In a bowl, combine ground turkey, breadcrumbs, beaten egg, 1/2 tablespoon Worcestershire sauce, dried parsley, allspice, nutmeg, salt, pepper, and the cooled onion and garlic.
Place the meatballs on a lightly greased baking dish and bake in the preheated oven for about 13-18 minutes, or until they reach an internal temperature of 165°F.
In a skillet, heat remaining olive oil. Sprinkle in flour and stir for 1 minute to form a roux. Gradually whisk in chicken broth and cook until the sauce thickens. Add remaining Worcestershire sauce and Dijon mustard.