Preheat oven to 350°F. Spray the bottom of a 9x13-inch pan with cooking spray.
Slice the King's Hawaiian rolls in half horizontally with a long serrated knife. Place the bottom half of the sheet of rolls into a 9x13-inch baking dish that has been sprayed with cooking spray to keep the sliders from sticking.
1 (12-count) package King's Hawaiian rolls
Spread a thin layer of Dijon mustard on the cut side of the rolls, then add a thin layer of mashed potatoes.
2 Tablespoons dijon mustard, 1 cup mashed potatoes
Add the turkey, piling it up as high as you would like. I like to shred the turkey by hand for the pulled texture, but you could used sliced turkey or even chop it if you prefer. Sprinkle the turkey with a generous amount of coarse black pepper.
1 pound shredded or sliced leftover turkey, 1 teaspoon coarse black pepper
Use the back of a spoon to spread the cranberry sauce over the turkey so you get some in every bite of these little sandwiches, then pile the stuffing on top of that in an even layer. Cover with the top half of the sliced rolls.
1 cup cranberry sauce, 2 cups stuffing, 6 slices provolone, havarti, or muenster cheese
Melt the butter in a microwave-safe bowl, then stir in the minced onion, Worcestershire sauce, and chopped parsley. Drizzle or brush the buttery topping over the sliders, making sure to coat the tops of each roll.
6 Tablespoons salted butter, 2 teaspoons minced dried onion, 1 teaspoon Worcestershire sauce, 1 teaspoon finely chopped fresh parsley
Wrap the pan in aluminum foil and bake for 20 minutes. Remove the foil and finish baking for another 5-10 minutes until toasted on top and heated all the way through.
Use a large, sharp knife to slice the sliders apart to separate them and serve immediately while hot.