01 -
Position your oven rack right in the center and preheat to a nice 350°F so everything bakes evenly.
02 -
Pop that butter in a microwave-safe bowl and melt it for about 20-30 seconds until it's liquid gold. If you prefer, you can melt it gently in a small pan on the stove instead. Whisk in the Dijon mustard, Worcestershire sauce, onion powder, and salt until you have a smooth, flavorful mixture.
03 -
Keep those rolls connected and carefully slice the entire package in half horizontally using a sharp serrated knife. Nestle the bottom half snugly into your 9x13-inch baking dish (or 7x11 if that's what you have).
04 -
Start by laying 6 slices of Swiss cheese over the bottom rolls, overlapping them so every bit is covered. Next, fold and arrange your ham slices over the cheese - one slice per future slider works perfectly. Crown it all with the remaining 6 cheese slices, then gently place the top half of the rolls over everything like a cozy blanket.
05 -
Brush that delicious butter mixture all over the top of the rolls, making sure to get every corner. Sprinkle the poppy seeds evenly across the top for that bakery-style finish, then cover the whole dish tightly with foil.
06 -
Slide into your preheated oven for about 20 minutes until everything is heated through and the cheese is beautifully melted. Remove the foil and continue baking for another 7-8 minutes until the tops are golden brown. Let them rest on a cutting board for a minute, then slice into individual sliders with your serrated knife and serve while they're still warm and gooey.