Melt the butter mustard, poppy seeds, Worcestershire sauce and dried minced onion in a bowl. Set aside while you assemble the sliders.
Hawaiian rolls are connected when removed from the bag. You can leave them connected and then just cut horizontally through the center to make a top and a bottom.
This helps because then you can make one large sandwich and cut them after they bake!
Once you have the top and bottom, place the bottom rolls in a 9 x 13 baking pan.
Add half of the ham on the bottom, then half of the cheese, then ham and cheese again.
Place the Hawaiian roll tops back on, and then pour the butter mixture all over the top. Use a spatula to get all of the ingredients and poppy seeds out.
Since these are baked ham and cheese sliders, toss them in a preheated 350-degree oven for 20 minutes until the cheese is melted.
When they’re done, cut each roll individually. Serve warm!
Notes
Make Ahead & Storage You can assemble the sliders a few hours in advance—just wait to pour the sauce until right before baking. Cover and refrigerate for up to 5 hours. Store leftovers in an airtight container in the fridge and reheat the next day.To Keep Warm Keep sliders wrapped in foil in a 200°F oven until ready to serve, or wrap them individually to hold heat on the table.