Place pastry on a piece of parchment paper. Gently roll pastry out, to enlarge slightly and join the perforations. Make a small edge by pinching pastry edge all around and prick dough all over with the tines of a fork. Place parchment sheet holding dough onto a baking sheet. Bake dough according to package directions until golden.

Put onions and fennel into a large skillet with butter and olive oil. Cook over medium low heat for 15-20 minutes, or until they begin to caramelize.

Spread apples in an even layer on top of baked pastry. Top with and even layer of onions and fennel, then top with prosciutto. Return to oven and bake at 400 for 12-15 more minutes

Top with cheese if desired and return to oven 1-2 minutes to melt cheese.

Cut into squares to serve. Makes 12-16 squares.