Preheat your oven to 350°F (176°C). Spray a 9" x 13" casserole dish with cooking spray to prevent the rolls from sticking.
Remove the Hawaiian rolls from the packaging but do not break them apart. Use a large, serrated knife to slice the rolls in half so there is a top and a bottom for the sliders. Place the bottom half into the casserole dish.
Optional step: Heat the ham slices up in the microwave on 50% power until they are warm. This will give the sliders a head start in the oven and the cheese will melt more evenly as they bake.
Add a layer of ham and then a layer of cheese over the bottom-half of the rolls.
Spread the mayonnaise onto the underside of the top-half of the rolls. Lay it over the ham and cheese layer with the mayonnaise side facing down.
Melt the butter in a saucepan or in the microwave. Add the dijon mustard, onion powder, poppy seeds and Worcestershire sauce and whisk to combine. Pour the mixture evenly over the top of the sliders. Cover the dish with foil and let it sit on the counter for 10 minutes.
Bake the sliders covered for 20 minutes. Remove the foil and bake an additional 5-10 minutes.
Use a sharp knife to cut the sliders apart and serve.