"Two Thumbs Up" Pizza

5 cups coarsely chopped red onion s

4 cups thinly sliced leek s (about 4; white and pale green parts only)

cup dry red wine

1/3 cup balsamic vinegar

1/3 cup very finely chopped prosciutto (about 2 ounces)

2 tablespoons finely chopped fresh basil

1/4 teaspoon cayenne pepper

2 purchased 10-ounce fully baked thin pizza crust s

8 ounces Gorgonzola cheese , crumbled

1 tablespoon minced fresh rosemary