Preheat oven to 350°F Lightly grease a 9-inch square pan.
In a medium bowl, whisk together flour, baking soda, salt and nutmeg.
In the bowl of a food processor, blend bananas until smooth. Add in melted butter, eggs, sugar and vanilla and whizz until smooth and well-combined. Pour banana mixture into flour mixture and stir until just combined. Fold in chocolate chips.
Pour batter into prepared pan (it will be a thin layer).
Bake at 350F for 20-25 minutes, until a tester comes out dry.