Preheat your oven to 350°F (175°C).
Slice the slider buns in half horizontally and place the bottom halves in a baking dish.
Spread a thin layer of mayo and mustard on each bottom bun.
Layer 2 slices of turkey and 1 slice of cheese on each bun.
Place the top halves of the buns on the sliders.
Mix melted butter with garlic powder and onion powder, then brush generously over the tops of the buns. Sprinkle with poppy seeds if you like.
Cover the baking dish with foil and bake for 15 minutes. Remove the foil and bake for another 5 minutes until the cheese melts and the tops are golden.
Serve warm and enjoy!