In a large mixing bowl, combine the ground turkey, cranberry sauce, bread crumbs, egg, garlic powder, onion powder, salt, and black pepper. Mix until well combined.
Preheat the large skillet over medium heat. While the skillet heats, form the turkey mixture into 6 equal-sized patties.
Once the skillet is hot, add the patties and cook for about 5-6 minutes on each side, or until the internal temperature reaches 165°F (75°C).
During the last minute of cooking, place a slice of Swiss cheese on each patty, allowing it to melt.
While the patties are cooking, you can lightly toast the slider buns on a baking sheet in the oven at 350°F (175°C) for about 5 minutes, if desired.
Assemble the sliders by placing a turkey patty on the bottom half of each bun. Add fresh spinach or lettuce, if using, and a dollop of additional cranberry sauce on top. Place the top half of the bun over the filling.
Serve immediately and enjoy your cranberry turkey sliders!