01 - In a large bowl, combine ground turkey, egg, breadcrumbs, parsley, Worcestershire sauce, garlic powder, onion powder, salt, and pepper. Mix gently until just combined; avoid overmixing to maintain tenderness.
02 - Divide the mixture into 12 equal portions. Shape each portion into a small patty, ensuring it is slightly larger than the slider buns to account for shrinkage during cooking.
03 - Preheat a grill or skillet over medium-high heat. Lightly brush the surface with olive oil or spray with a nonstick cooking spray.
04 - Place the patties on the preheated surface and cook for 3 to 4 minutes per side, or until they are fully cooked through and an internal temperature of 165°F (74°C) is reached.
05 - During the final minute of cooking, place a half-slice of cheddar cheese on top of each patty. Cover the cooking surface briefly to allow the cheese to melt.
06 - Lightly toast the slider buns on the grill or in a toaster until golden brown.
07 - If desired, spread mayonnaise and Dijon mustard on the bottom half of each toasted bun. Layer with shredded lettuce, a slice of tomato, and a turkey patty with melted cheese. Top with a pickle slice and the other half of the bun.
08 - Serve the sliders immediately, or keep them warm by wrapping them in foil if transporting to an event.