Peel and dice the potatoes to approximately 1/2-inch cubes. Heat the olive oil in a large skillet and saute the onion, garlic and diced potato for 5 minutes. Add the tomatoes and ground chicken and keep cooking for another 3 minutes. Season to taste with salt and pepper. Transfer everything in a baking dish, pour the chicken stock in and bake covered for about 20 minutes. In the mean time mix together the yogurt, eggs and spices. When the potato is soft, pour the mixture on top of the chicken moussaka and bake uncovered until the topping sets and becomes nicely golden in color. Let the chicken moussaka rest out of the oven for 10 minutes before cutting and serving.