In a large bowl, combine the egg, grated Parmesan, 3/4 cup panko breadcrumbs, garlic powder, Italian seasoning, crushed red pepper, salt, and black pepper. Stir everything together until well mixed.
Wear food-grade disposable gloves, then add the ground chicken to the bowl. Use your hands to thoroughly mix the chicken with the other ingredients until evenly combined.
Spread the remaining 1 cup of panko breadcrumbs on a plate. Using a 1-1/2-inch scoop, form about 24 meatballs. Gently roll each one in the breadcrumbs to coat lightly, then set them aside on a plate.
Set the oven to preheat at 350°F (175°C) to ensure it's hot and ready for baking.
Heat 1 tablespoon of olive oil and 1 tablespoon of butter in a large, oven-safe skillet over medium heat. Add half of the meatballs and brown them on all sides, turning gently. Once browned, transfer the meatballs to a plate and wipe the skillet clean.
Add the remaining oil and butter to the skillet, then cook the rest of the meatballs, browning them on all sides just like the first batch.
Clean the skillet once more, then pour in the marinara sauce. Gently place the browned meatballs into the sauce, ensuring they are not fully submerged.
Bake the meatballs in the preheated oven for 25 minutes. Then, sprinkle shredded mozzarella over the top and bake for an additional 5 minutes, or until the cheese is melted and bubbly. Finish by garnishing with fresh parsley.