01 - In a large mixing bowl, combine the ground turkey, egg, breadcrumbs, fresh parsley, Worcestershire sauce, garlic powder, onion powder, salt, and black pepper. Mix gently until just combined; avoid overmixing to maintain tenderness.
02 - Divide the turkey mixture into 12 equal portions. Shape each portion into a small, uniform patty, ensuring it is slightly larger than the slider buns, as they will reduce in size during cooking.
03 - Preheat a grill or a large skillet over medium-high heat. Lightly brush the surface with olive oil or apply a nonstick cooking spray.
04 - Cook the turkey patties for 3 to 4 minutes per side, or until they are thoroughly cooked through. Verify doneness by ensuring an internal temperature of 165°F.
05 - During the final minute of cooking, place a halved slice of cheddar cheese on top of each patty. Cover the cooking surface to facilitate melting of the cheese.
06 - Lightly toast the slider buns on the preheated grill or in a toaster until golden.
07 - Spread mayonnaise and Dijon mustard on the bottom half of each bun, if desired. Layer with shredded lettuce, thinly sliced Roma tomatoes, a turkey patty crowned with melted cheese, and a pickle slice. Complete with the top half of the bun.
08 - Serve the sliders immediately, or keep them warm by wrapping them in foil if transporting to an event.