Preheat oven to 350 F and line a sheet pan with parchment paper.
Add the onion, garlic, parsley and basil to a food processor and pulse until finely chopped. Transfer to a medium sized bowl.
Add 3/4 cup of marinara, bread crumbs, parmesan, egg, Italian seasoning, salt and pepper. Stir to combine. Add the ground chicken and mix to combine.
Transfer the mixture to the prepared sheet pan and shape into an 8x4 inch loaf.
Bake for 45 minutes.
Remove from the oven and brush with remaining 1/4 cup marinara sauce. Top with the shredded mozzarella and continue baking for 10-15 minutes.
Meanwhile, melt the butter in a medium skillet over medium heat. Add the panko and garlic powder. Toast, about 3-4 minutes. Transfer to a small bowl and let cool several minutes, before stirring in the parmesan, parsley and basil. Season with salt and pepper.
Garnish the meatloaf with some of the bread crumb mixture and a sprig of basil. Serve remaining bread crumb mixture and more marinara sauce on the side.