In a large bowl, combine the ground chicken, chopped onion, minced garlic, parsley, cumin, coriander, paprika, salt, black pepper, and cayenne pepper (if using). Mix until well combined.
Shape the mixture into oval-shaped kofta (about 2-3 inches long) and place them on a baking sheet.
Preheat your grill or grill pan over medium-high heat. Lightly brush the kofta with olive oil.
Grill the kofta for about 5-7 minutes on each side, or until fully cooked and browned. Alternatively, you can bake them in a preheated oven at 400°F for 20-25 minutes.
While the kofta is cooking, prepare the garlic yogurt sauce by mixing the Greek yogurt, lemon juice, minced garlic, salt, and pepper in a small bowl. Adjust seasoning to taste.
Serve the kofta warm with the garlic yogurt sauce on the side, along with pita bread or rice.