Spread butter on the inside of each side of the bun. Sprinkle the Parmesan over the butter, adding more if desired. Place buns in a large skillet Parmesan side down, and cook over medium heat until Parmesan has browned and is crispy. Place toasted buns on plates.
Make lemon aioli:
Mix mayo, lemon juice, and lemon zest together in a small bowl until it’s smooth. Set aside.
Make chicken scallopini:
Sauté Gardein chick’n scallopini from frozen in a non-stick pan over medium heat for 1 minute each side. Add 3 tablespoons of water, cover, and cook for 2 minutes. Uncover, turn, and cook for an additional 1-2 minutes. Internal temperature should be 165 ° F. Let rest for 1 minute before serving. Do not overcook – it’s not meat.
Assemble sandwiches:
Place a handful of arugula on the bun, and top with chick’n scallopini. Drizzle lemon aioli over the top.