Preheat your oven to 400°F (200°C).
In a large mixing bowl, combine ground chicken, breadcrumbs, Parmesan, parsley, garlic powder, oregano, egg, salt, and pepper.
Shape the mixture into meatballs, about 1.5 inches in diameter.
Place the meatballs on a baking sheet lined with parchment paper.
Bake the meatballs for 20-25 minutes, or until golden brown.
While the meatballs are baking, prepare the tzatziki sauce.
In a bowl, mix the yogurt, grated cucumber, minced garlic, lemon juice, and salt.
Serve the meatballs warm with tzatziki sauce on the side.