Preheat oven to 350°F and grease an 8×11-inch baking dish with nonstick spray. Without separating the rolls, slice in half horizontally. Place bottom half of attached rolls in baking dish.
Layer with half of the cheese, the ham, the turkey, then the remaining cheese. Place top half of rolls on top.
In a small bowl, whisk together the butter, egg, and Dijon mustard until well combined. Brush over top of rolls.
Cover loosely with foil, using toothpicks to lift foil if needed and bake 15 minutes.
Remove foil and bake 10 minutes more.
Let cool slightly, then score sliders with a sharp knife to separate for easy serving. Sprinkle with powdered sugar and serve with raspberry jam for dipping. Enjoy!
