Heat broiler (or toaster oven). Place 8 square whole-wheat crackers on a broiler-proof (or toaster-oven) baking sheet.
On a lightly floured surface, roll and stretch dough into a 12-by-16-inch oval (or as large as will fit on baking sheet); transfer to sheet.
Dividing evenly, top crackers with 3 tablespoons jarred marinara sauce and 3 tablespoons shredded part-skim mozzarella cheese. Top half of the crackers with 1 tablespoon thawed frozen chopped broccoli.
