Melt your butter, honey and sugar in a pan until all the sugar is dissolved and you have a syrup-like consistency.
Stir in your oats, mashed banana and cinnamon until thoroughly combined.
Line your baking dish with paper and spoon the mixture in, smoothing the surface with the back of a spoon.
Bake in a preheated oven at 180C for 30 minutes and then leave to cook before cutting into pieces and enjoying.
Notes
You could add raisins too if you wanted, or we also love adding dedicated coconut to it (sub out 75g of the oats for 75g of the coconut). If you wanted a finer ground flapjack you can pulse the oats in a blender for a few seconds first.