MAKE THE BURGER MIXTURE. Preheat oven to 375 degrees F. In a large bowl, combine ground chicken breast, parmesan cheese, bread crumbs, basil, garlic, salt, pepper, and Italian seasoning. Gently mix with a fork or your hands until just combined, trying not to over-mix or overly compact the mixture.
SHAPE & BROWN BURGERS. Divide the burger mixture into 4 equal sections and shape each into a patty just larger than the size of your bun (since they’ll shrink a bit during cooking). Slightly indent the center of each burger. Heat 1-2 TBSP oil in a large skillet over medium heat and brown the butters 4-5 min per side, or until golden brown. Make sure to heat the oil in the skillet before adding the burgers, so they’re less likely to stick!
WHILE CHICKEN COOKS, PREP BUNS. In a small bowl, combine softened butter, garlic, and parsley and stir until evenly blended. Open each bun and spread garlic butter on the cut side of each half of the buns. Place buns on a sheet pan. Bake 8-10 min in preheated oven to toast buns.
TO FINISH BURGERS ON THE STOVE (FASTER). Remove browned burgers from the pan. Add 1 ⅓ cup marinara sauce to the saucepan and stir to scrape up any browned bits from the bottom of the pan. Return burgers to the pan and top with the remaining ⅓ cup marinara sauce. Cover the pan with a lid and simmer 4-5 min. Top each burger with ¼ cup grated mozzarella cheese and cook covered another 4-5 min or until the cheese is melted and the interior of the burgers has reached 165 degrees F.
TO FINISH BURGERS IN THE OVEN. Pour 1 ⅓ cup marinara sauce in a 9x9 baking pan. Add browned burgers to the pan and top with the remaining ⅓ cup marinara sauce. Top each burger with ¼ cup grated mozzarella cheese. Bake 20-25 min or until the internal temperature of the chicken reaches 165 degrees F. Garnish with pepper, parsley, or more Parmesan, to taste.
SERVE & STORE. Serve chicken parmesan burgers on toasted buns and top with arugula, if desired. Store leftover burgers in an airtight container in the fridge 2-3 days.