Preheat the oven to 350F. Cut the 1 package (12) slider buns/rolls in half through the middle to create two "slices" of slider bun sheets.
Place the bottom half of slider buns in a casserole dish. Set aside.
In a skillet, melt 1 Tablespoon butter over medium-heat.
Whisk 12 large eggs in a medium-sized bowl until fully blended. Pour into skillet, season with salt and pepper (to taste) and stir constantly, until eggs are scrambled and fully cooked. Remove skillet from heat.
Place6 slices ham in an even layer over the bottom slider bun sheet you placed in a casserole dish from earlier. Add scrambled eggs and then 6 slices cheese.
Then, place the top half of slider bun sheets over the slider fillings.
In a separate bowl whisk together 1/2 cup (1 stick) salted butter, melted, 2 teaspoons dried minced onion, 1 teaspoon dijon mustard, 1 teaspoon Worcestershire sauce and 3/4 teaspoon poppyseeds. Pour the sauce (or brush it on with a pastry brush) over the sliders so it covers the bread evenly.
Cover baking dish with aluminum foil and cook for 25 minutes with the foil on Then take off the foil and continue to cook for 5 more minutes to slightly toast the buns and the spices on top.
Video
Notes
Updated to add: I updated this recipe from the original with a new sauce. After some experimentation, we really ended up loving this with a seasoned butter on top but it is optional if you prefer.