In a deep, medium-size saucepan, whisk flour, sugar and cinnamon into milk. Stir in quinoa and water. Bring to a boil over medium-high heat, stirring occasionally.
Reduce heat to low, cover and simmer, stirring often, for 20 minutes. Stir in diced apple, cover and simmer, stirring often, for about 5 minutes or until quinoa and apple pieces are tender. Remove from heat and let stand, covered, for 3 minutes.
Spoon into bowls and sprinkle with nuts or sunflower seeds (if desired) and cinnamon. Add a hint of maple syrup or brown sugar, if desired.