1. Place thawed flatbreads on sheet pans that have been lined with parchment paper. Brush each sheet with oil, sprinkle grated parmesan cheese, and the granulated garlic.
2. Distribute pizza sauce evenly over the entire surface of each flatbread. Then individually place the portobella mushroom slices evenly on the sauce.
3. Distribute shredded mozzarella cheese evenly. Add vegetables over the cheese. Place topped flatbreads in a preheated 400 degree F oven for approximately 15-18 minutes, until the vegetables are golden brown or caramelized and the cheese has melted with slight areas of brown. Cut each flatbread into 3 equal sized pieces (each piece 4" x 12").