Gratin of zucchini (green squash) and potatoes

Quarter 3-4 zucchini by cutting lengthswise and cutting resulting halves in two. Short ones need to be cut only lengthwise. It all depends on the size of your gratin form.  

Saute 1/2 onion and 1 clove garlic in olive oil. Add ground cumin, black pepper, paprika and dash of chili or cayenne pepper. Add pieces of zucchini and sauté lightly. Add 1/2 to 3/4 cup of chopped tomatoes (tinned or fresh), add salt, cook covered on low fire until zucchini is softening. Continue cooking uncovered, stirring carefully, until sauce is just about dry.

Place zucchini pieces, cut side up, into greased gratin dish. Top with sauce.  
While preparing the zucchini, boil potatoes, peeled and cut in halves, in salt water. Add 2 unpeeled (or more) cloves of garlic. When potatoes are done, strain. Peel boiled garlic and add to potatoes. Mash adding some olive oil to get smooth consistency. Season with paprika (or chili powder) and black pepper. Cover zucchini pieces with mashed potatoe, smooth down firmly. Use fork to draw patterns on surface, sprinkle with cheese (optional), decorate with flaked dry chillies or paprika and few black olives (optional), top with a few drops of olive oil or butter flakes. Bake in moderate oven for about half an hour.