Preheat oven to 180°C (350°F) and lay baking paper into a brownie pan
Cut apples into chunks, then add to a blender with eggs, cocoa powder & baking powder. Blend on high until smooth and free of lumps. If using maple syrup, add to blender too. Transfer mixture to the brownie pan.
Bake for 20 to 27 minutes, or until cooked through. Let cool completely at room temperature before slicing.
