Slice the rolls in half widthwise to create one large bottom and one large top bun. Transfer the bottom half to a sheet pan and set the top half aside.
Layer the sliders first with porchetta, then with ham, Swiss cheese, and pickles.
Stir the mayo, mustard, and garlic together in a small bowl.
Spread the mixture on the top buns.
Firmly press the top buns onto the bottom buns.
Brush the buns with melted butter on top.
Place in the oven and bake for 20 minutes, or until the cheese is melted.
Remove from the oven and immediately (while the sliders are still warm) use a second sheet tray to press the buns down slightly.