Heat grill (or oven) to 450 degrees. Bake flatbread 3-5 minutes, until it begins to crisp.
Spread pesto, followed by hummus, over flatbread, then layer mushrooms, corn, and asparagus. Top with shredded mozzarella cheese.
Place on grill, close lid and cook 3-5 minutes (if using oven, broil approximately 3 minutes). Drizzle with olive oil; sprinkle with red pepper flakes, if desired. Add salt and pepper before serving.