Preheat your oven to 400*F. Cook the quinoa according to package directions, fluff, and set aside.
Heat the olive oil in a medium skillet over medium heat. Add the onion and garlic and saute until fragrant and tender Approx. 2-3 minutes).
Add the onion/garlic mix, red pepper flakes, and the basil to the quinoa. Place this entire mixture into a casserole dish that has been sprayed with cooking spray.
Place tomato slices and mozzarella circles on top of the quinoa, alternating between the two.
Bake for 25-30 minutes or until the cheese is bubbly and turning a golden brown.
Prepare the balsamic reduction drizzle while the casserole is baking: In a small sauce pan, heat the balsamic vinegar until it simmers and let simmer for 4-5 minutes, until the liquid reduces and becomes thicker, like syrup consistency.
Drizzle the reduction on top of the cooked casserole and garnish with fresh cracked pepper. Serve by itself or with your favorite protein. Enjoy it messy!