Chop the zucchini and tomatoes. Dice the feta and place in a baking dish with the vegetables.
Chop the onion and garlic into small pieces. Put in a pan with a little oil and fry. Cut the chicken breast fillets into small cubes and fry them all over in the pan for a few minutes so that it is browned on the outside but not done on the inside. Season with salt and pepper.
Preheat the oven to 180 ° C top / bottom heat.
Add the chicken to the vegetables in the baking dish and mix everything a little. Drizzle with 1 - 2 tablespoons of olive oil and season a little more.
Fry in the oven for about 20 minutes on the middle rack.