Preheat oven to 400 degrees Fahrenheit
Line a sheet pan with aluminum foil
Cut the eggplants in half
Score the meat of the eggplant in a crisscross pattern being careful not to cut through the skin
Add olive oil, salt, and pepper
Roast the eggplant in the oven for 30 minutes
Remove from oven and let them cool
When the eggplant cools, remove the filling with a spoon leaving a bit of pulp to ensure they are strong enough to be stuffed
Reserve eggplant pulp and cut into small chunks
Meanwhile heat 2 teaspoons of olive oil in a skillet over medium heat
Add the onions and saute until tender for 3-4 minutes
Add the garlic and saute one minute more
Add the oregano and cinnamon
Add the meat and break into small chunks while it cooks
Add the olives and tomato puree
Season with salt and pepper
Stuff the eggplants with this filling
Crumble feta cheese on top
Bake for 5-10 more minutes
Remove from heat and add the tzatziki sauce if you would like