Cover a rimmed baking sheet with parchment paper or aluminum foil (note: if using foil spray lightly with a non-stick spray).
Leaving the rolls intact, slice them in half on the horizon.
Starting with the bottom buns placed on the baking sheet, layer the corned beef, sauerkraut, thousand island dressing, Swiss cheese, followed by the top of the buns.
In a microwave safe bowl melt 2 tablespoons butter and brush over the top of the buns and sprinkle with poppy seeds.
Place tin foil over, loosely, and bake for 15-20 minutes. Remove the foil to brown the tops slightly, and enjoy!
Notes
Store leftovers for up to 2 days, and you can easily reheat the sliders the toaster oven if you have one! (Or a microwave or even reheat at a low temperature in the oven.)