Cut zucchini in thin slices. Preheat frying pan, spray with cooking oil and brown each a bit.
While frying zucchini, sprinkle salt to taste. I would not sprinkle too much because a lot of the flavor will come from ketchup.
In another frying pan sauté onions and carrots, until golden brown. Add ketchup, cook for another minute.
Place zucchini in ceramic dish, add garlic cloves and top sautéed ingredients. Bake at 400F for 30 minutes.