In a large bowl, combine flax meal and water. Let stand until thickened.
Add vegetable oil, sugar, mashed bananas and vanilla extract, and mix until incorporated.
Sift in baking powder, baking soda, salt, cinnamon and flour. Stir until just combined. Fold in chocolate chunks.
Divide batter between a lined muffin tin. Bake for 13-15 minutes until a toothpick or cake tester comes out clean when poked through the middle. The edges should be golden and top domed. Remove from tin within a few minutes and let cool on a wire rack.