If You Don't Have a Panini Grill
Heat skillet on medium heat. Cook sandwich 5 min. on each side or until cheese is melted and sandwich is golden brown on both sides, gently pressing down top of sandwich with a spatula to flatten slightly as it cooks.
Substitute 2 tsp. KRAFT Tuscan House Italian Dressing for the mayo.
If packing for a brown-bag lunch, spread mayo on inside of sandwich and serve cold.