Preheat the Oven: Preheat your oven to 350°F (175°C).
Prepare the Buns: Cut the slider buns in half. Place the bottom halves in a baking dish.
Assemble the Sliders: Spread mayonnaise on the buns. Layer Swiss cheese, ham and Swiss cheese on top. Cover with the top halves of the buns.
Make the Glaze: In a bowl, mix together melted butter, Dijon mustard, minced onion, poppy seeds.
Apply the Glaze: Brush the glaze generously over the top of the sliders, making sure to cover them evenly.
Bake: Cover the baking dish with aluminum foil and bake for 15 minutes. Then, remove the foil and bake for an additional 5-10 minutes, or until the tops are lightly browned and crispy.
Serve: Let the sliders cool for a few minutes before serving.
Keyword Ham and Cheese Sliders, Ham and Swiss Sliders