Prepare the quinoa as directed (preferably with chicken broth instead of water - this gives it more flavor). While quinoa cooks, dice cherry tomatoes and chop spinach leaves, then set aside. Next, in food processor combine 1 cup feta, skim milk, garlic, lemon juice, and parsley, blending until smooth.
When ready, stir artichoke hearts, cherry tomatoes, and spinach into quinoa, plus 1 tbsp oil from artichokes, stirring well. Pour over with feta sauce, then season with onion powder and salt & pepper, combining thoroughly.
Transfer mixture to oven safe casserole dish, spreading evenly. Top with remaining feta and mozzarella (or cheddar), then bake at 400F for 15 minutes until top has melted. Immediately plate and serve.