Place the eggplant and zucchini slices with the cherry tomatoes, onions, garlic, olives and pepper slices in a large mixing bowl. Coat with olive oil and lemon juice, and season with thyme, garlic powder, salt and pepper.
Transfer into a baking pan and bake for 20 minutes.
Remove from the oven and add the feta slices.
Return to the oven and bake for 15 more minutes until golden brown. Serve hot.