Preheat the oven to 350°F (175°C).
Slice the slider buns horizontally, keeping them in one piece if possible.
Layer the bottom half of the buns with sliced turkey breast and cheddar cheese evenly.
Place the top halves of the buns over the layered fillings.
In a small saucepan, melt the unsalted butter over low heat.
Stir in the Dijon mustard and poppy seeds until combined.
Brush the butter mixture generously over the tops of the slider buns.
Arrange the sliders in a single rectangular baking dish, slightly pulling them apart to show the layers.
Bake in the preheated oven for 20 minutes or until the tops are golden brown and cheese is melted.
Remove from oven and let sit for a few minutes before serving.