Preheat oven to 425F. Line 9-inch springform cake pan with parchment paper and spray with oil. Set aside.
Rinse quinoa and place in blender with water, baking soda, salt, and olive oil until thick and smooth.
Pour batter into cake pan, transfer to oven and bake for 15 minutes. Remove, then flip and bake for an additional 15 minutes, until golden and crisp on edges.
Top crust with tomato sauce, mozzarella and spinach. Bake until cheese is bubbly and spinach is crisp.
Top with salt and pepper to taste.