Heat oil in skillet over medium heat. Add garlic, onion, bell peppers, and mushrooms. Cook, stirring frequently, for about 8 minutes or until veggies are soft. Remove from heat and stir in the spinach. Set aside. Place flatbread on grill or stovetop gas flame; grill for a couple of minutes or until lightly browned, turning once. Place all four flatbread on a baking sheet. Spread surface of flatbreads with hummus. Sprinkle parmesan cheese on top of hummus, then top with veggies and mozzarella cheese. Sprinkle with oregano and red pepper flakes. Place in 400ºF oven and bake for about 5 minutes or until cheese is melted. Drizzle with balsamic vinegar. Enjoy!