Preheat oven to 400 degrees and line a baking sheet with foil. Cut your rolls in half, if not already done. Brush the insides of the rolls with EVOO.
Heat a grill pan over high heat. Grill the oil side of the ciabatta rolls for 2-3 minutes until bread is toasted and has grill marks. Repeat with other rolls.
Pile the pot roast on top of the bottom of the rolls, using on the beef, onions and gravy. Lay a 1/2” slice of fresh mozzarella on each sandwich.
Bake for 5-10 minutes (just the bottom half of the sandwich) until the pot roast is heated and the mozzarella starts to become melted.
Turn the broiler on high. Broil until the mozzarella is completely melted and bubbly, only 2-3 minutes MAX. Do not walk away, be careful not to burn.
Remove from oven. Top with top half of roll and cut in half. Enjoy!
