Preheat the oven to 170°C / gas mark 5. Grease and line a tray bake tin with softened butter and baking parchment.
Peel and mash the bananas and set aside.
Into a saucepan, add the unsalted butter, honey, maple syrup, caster sugar, vanilla extract and almond or peanut butter and melt together over a low heat.
Add the hot mixture to a bowl with the rolled oats and bananas and stir together. Give everything a good stir before tipping into the tin and baking in the oven for 25-30 minutes until golden. Allow to cool.
Put the dark chocolate into a heatproof bowl set over a pan of gently simmering water, not letting the bottom of the bowl touch the water. Melt gently, stirring occasionally.
Use a dessert spoon to drizzle the molten chocolate over the flapjack, scatter with peanuts and allow to set. Cut into slices to serve.
Really chewy bars, made in a flash and make use of those really ripe bananas in the fruit bowl. The drizzle of chocolate is definitely worth it!