Preheat oven to 375. Place the pancetta slices on a parchment lined rimmed baking sheet. Bake until golden brown, turning over once. This takes approximately 15 minutes.
While the pancetta crisps, slice the tomato and mozzarella.
Make a spread by combining the mayo, parmesan, balsamic vinegar and salt & pepper to taste. Refrigerate until you assemble the sandwiches.
When the pancetta has cooked, drain on paper towels to remove excess grease. Toast the King's Hawaiian bread slices.
Spread the balsamic mayo on the bottom slice of toasted King's Hawaiian bread. Top with two pieces of the fresh mozzarella.
Drizzle half of the olive oil on top of the mozzarella, then top with 4 slices of the pancetta. Top the pancetta with the sliced tomato and lettuce. Spread the pesto on the top slice of toasted King's Hawaiian bread and place on top.
Repeat the process for the second sandwich. If desired, cut each sandwich in half with a serrated knife.