1. Preheat oven to 375°F. Line 12-cup muffin pan with paper liners. Spray liners with cooking spray.
2. Whisk eggs in large bowl. Whisk in maple syrup, oil, and vanilla extract, then stir in apple and quinoa.
3. Combine flour, sugar, flaxseed, cinnamon, baking powder, baking soda, and salt in separate bowl. Whisk until combined.
4. Make well in flour mixture, and pour in half of apple mixture. Stir to combine. Add remaining apple mixture, and stir until batter is smooth.
5. Divide batter among prepared muffin cups, and bake 20 minutes, or until toothpick inserted in center of muffin in center of pan comes out clean. Cool 5 minutes before serving.