In small skillet, cook Pancetta until crisp. Drain on paper-towel lined plate; set aside.
Heat medium-sized skillet on medium-high heat. While skillet is heating, assemble sandwiches. Place one slice of mozzarella cheese on bread heel. Top with Pancetta, 2 Tbsp. Parmesan cheese (per sandwich), and sliced roasted red peppers. Place other half of bread slice on top. Butter the tops of the sandwiches.
Melt 2 tablespoons of butter in the skillet. Place sandwiches in skillet with buttered tops facing up. Let cook for 2 minutes and carefully flip sandwiches over. Press down to flatten slightly. Cook for about 2 more minutes or until bread is lightly browned. Serve warm.