Preheat the oven to 400°F (200°C).
In a large bowl, combine ground chicken, breadcrumbs, and Parmesan cheese.
Add chopped parsley, minced garlic, oregano, salt, and pepper.
Crack in the egg and mix until well combined.
Gently fold in the crumbled feta cheese.
Shape the mixture into meatballs, about 1.5 inches in diameter.
Place meatballs on a baking sheet lined with parchment paper.
Bake for 20 minutes or until cooked through and golden brown.
While baking, prepare tzatziki sauce by mixing yogurt, cucumber, garlic, and dill.
Serve warm with tzatziki and your choice of sides.