Heat oven to 350°F; line a baking pan with parchment.

Split connected rolls; spread mustard on both cut surfaces.

Layer bottom with roast pork, ham, drained pickles, and Swiss. Replace top slab.

Brush with butter; cover with parchment. Set a second pan on top as a light weight.

Bake 15 minutes; remove weight and parchment. Bake 5 to 8 minutes more until center reaches 165°F.

Rest 5 minutes; cut into 12 sliders.