In a large mixing bowl, combine the ground chicken, breadcrumbs, Parmesan cheese, parsley, minced garlic, egg, oregano, salt, black pepper, and red pepper flakes (if using). Mix until just combined; do not overmix.

Preheat your oven to 400°F. Line a baking sheet with parchment paper.

Using your hands, form the mixture into meatballs, about 1 to 1.5 inches in diameter, and place them on the prepared baking sheet.

Drizzle the olive oil over the meatballs and bake in the preheated oven for 20-25 minutes, or until they are cooked through and golden brown.

While the meatballs are baking, heat the marinara sauce in a saucepan over medium heat.

Once the meatballs are done, add them to the marinara sauce and let them simmer for 5-10 minutes to absorb the flavors.

Serve the meatballs with pasta, on a sub roll, or on their own with extra sauce on the side.