Preheat the oven to 180ÂșC. Line a 20 x 30cm baking dish with baking paper.
Process the flour, oats, almond meal and quinoa flakes in a processor for approximately 10 seconds until it resembles flour.
Add the apple puree, maple syrup, cinnamon and vanilla extract. Process until combined.
Pour the mixture into the baking tray and smooth with a spoon so that it is even.
Bake for 25 mins, until browned on top.
Notes
The large baking dish means that the slice is quite thin, and cooks through. If you have a smaller dish, use a lower cooking temperature and bake for longer to ensure that it cooks the whole way through.