Preheat oven to 350ºF. Line a baking sheet with parchment paper and set aside.
Add tahini, syrup, banana, flax egg, and vanilla in a large bowl. Mix until combined. Add oats, quinoa, baking powder and salt to the bowl and stir together. Fold in the coconut and chia seeds if using.
Spoon 2 tablespoons of dough onto the baking sheet and repeat until no dough remains.
Bake cookies on center rack for 15 - 18 minutes until edges are golden brown. Remove and let cool on the pan for 5 minutes then transfer to a wire rack and cool completely.
Enjoy at room temp or slightly reheated in a microwave.