1. Cook quinoa as per package instructions and set aside. Preheat oven to 375 degrees. Spray or oil 9 x 13 baking dish.
2. Preheat large non-stick skillet on medium heat and swirl oil to coat. Add onion and garlic, saute until translucent, stirring occasionally.
3. In a small bowl, whisk milk with cornstarch and add to the skillet along with artichoke hearts, spinach, Parmesan cheese, 1/2 cup mozzarella cheese, quinoa (fluff with a fork a bit before adding), 1/2 tsp salt and pepper. Stir until cheese is melted.
4. Transfer mixture to prepared baking dish, level and sprinkle with remaining 1/4 cup cheese. Bake uncovered for 25 minutes. Serve hot.Store:

Refrigerate in an airtight container for up to 3 days or freeze leftovers for up to 3 months.

Freeze:  Assemble, tightly wrap with plastic and then foil (after it cools), and freeze for up to 3 months.  Thaw in the fridge overnight and bake as per instruction +15 minutes.

Make Ahead: Assemble, cover and refrigerator for up to 48 hours.  Bake as per instructions