PREHEAT oven to 425° F.
PLACE pizza crusts on a large baking sheet. Spread pesto evenly over crusts; arrange tomatoes over pesto. Dollop with cheese; sprinkle with prosciutto.
BAKE for 12 to 15 minutes or until tomatoes are soft and cheese is melted.
WHILE pizzas are baking, prepare Balsamic Glaze. Bring balsamic vinegar to a boil in a small saucepan. Cook for about 2 minutes or until reduced by half.
REMOVE pizzas from oven; drizzle with Balsamic Glaze and sprinkle with basil.