Carve out the peppers' insides and gently pierce them in places with a knife. Heat oil and fry the chopped onions and leeks, pouring in some water as well. Add the washed and drained rice and once it fries, add 2 1/2 cups of water.
Add the broth cubes and all the spices. Once the rice absorbs the water, remove it from the heat. Allow the mixture to cool and absorb all the liquid. Add the parsley and feta cheese. Fill the peppers and arrange them in a greased tray.
Spread stuffing around them if there is still some left over. Add another 2 cups of hot water and put the peppers to bake until ready. Optionally, you can flip them over once during baking.
Once ready, pour on the beaten together yoghurt and eggs with a little salt over them. Bake until the topping hardens.