Duck Pizzas with Caramelized Pineapple

This dish was inspired by a delicious appetizer I had at Bonnars Restaurant in Haddington in East Lothian, Scotland; the chef whipped it up for me as I am allergic to mushrooms. It is quite delicious, and you can make your pizzas bigger or smaller at will. Concasse of tomato is merely homemade tomato paste, made by peeling and seeding tomatoes and cooking them very slowly with a little oil and seasoning until the juice is first expelled, then evaporated.