Preheat oven to 375. Chop onion and mince garlic.
Add olive oil to a medium skillet and add in onion and garlic. Cook until onion is translucent, about 5 min. Add in ground meat. Using a spatula or flat spoon, break up the meat and integrate it with the garlic and onions. Cook until meat is browned, but don’t overcook as the meat will be transferred and cook in the oven.
Coat cocottes in oil or butter and add 2 layers of zucchini to the bottom. Add a layer of cooked meat mixtures, followed by a layer of feta crumbles. Repeat the layers until you reach the top. When the layers cook they shrink so you’ll want to push down the layers as you go to maximize the amount you get. Sprinkle more feta and a little grated parmesan on top and bake for 20-25 min with the top on.
After 20 min, check and everything should be bubbling together and slightly browned. Switch oven to broil and slice mozzarella. Add to top of each cocotte and broil for about 5 min or until nicely golden brown. Enjoy!