Mix all ingredients with one another except for the tuna as if for a sponge cake. Then fold in the chopped tuna. Place in a greased baking pan dusted with breadcrumbs. I use a loaf pan.
Bake at 180 ° C for 30 minutes on the middle rack. Let cool and serve sliced.
Alternatives to tuna:
Olives, chicken (cooked), dried tomatoes with mozzarella and basil, ham, mushrooms. Just anything you might like, but not too watery.