Preheat oven to 350F. Spray a 9×13-inch pan with cooking spray and set aside.
Using a large serrated knife, slice the entire package of rolls in half. You don't want to cut or separate individual rolls, but rather make it so you have a bottom half of all the rolls and a top half of all the rolls (see photos in this post). Place the bottom half of the rolls in the prepared pan.
Evenly layer half of the turkey over the rolls. Spread an even layer of cranberry sauce on top. (Make sure you have a good thick cranberry sauce so the bottom of the rolls don't get soggy!)
Evenly layer the cheese. (I do 2 layers of muenster cheese). Evenly layer the remaining turkey. Add the top half of the rolls and set aside.
To a medium microwave-safe bowl, add the butter and melt. Stir in 1 and 1/2 teaspoons of the turkey gravy packet, dijon mustard, poppyseeds, dried minced garlic, and onion powder. Whisk to combine.
Evenly and slowly pour the butter mixture over the rolls. Use a spatula or pastry brush to spread the mixture over the tops. Some of the mixture will pool at the base of the rolls -- that's okay.
Cover the sliders with foil and allow rolls to stand at room temperature for 5 minutes. Then bake in preheated oven (covered) for 18-25 minutes or until the cheese has melted and turkey is heated throughout. Uncover and bake the sliders for another 3-5 minutes or until the sliders are done to your desired preference.
Make sure to watch your sliders carefully to avoid burning. The bake time will vary based on the pan you used, the current climate/humidity, and differences in ovens.
Meanwhile, add the remaining gravy mix to a small pot. Add in 3/4ths cup of cold water and prepare the gravy according to package instructions. Serve alongside finished sliders!
Slice into individual sliders and serve immediately with a side of gravy! Sliders are best served right after being removed from the oven. These don't store or re-heat very well.
*I highly recommend a thick homemade cranberry sauce to ensure these rolls don't get soggy and have the right amount of sweetness.