Preheat the oven to 180°C/350°F/gas mark 4 and line a 7” x 7” baking tin with parchment paper. Make sure you also line the sides of the baking tin. This will make it easier to remove the flapjack from the tin after it is baked.
Peel the bananas, place them in a mixing bowl and mash them with a fork until they become runny. Add the oats, sunflower seeds, pumpkin seeds, raisins and walnuts to the mixing bowl.
Then transfer the peanut butter, maple syrup and coconut oil to a small pan on a low heat. Stir to combine and leave on the heat until melted.
Pour the peanut butter liquid into the mixing bowl and stir until the dry ingredients are fully coated with the wet ingredients.
Transfer the flapjack mix to the pre-lined baking tin and use a spatula to level the mixture.
Bake the flapjack in the preheated oven for 30 minutes.
Remove the flapjack from the oven and leave to cool in the tin for 5 minutes. This will set the flapjack so it doesn’t break when you move it.
Remove the flapjack from the tin and leave to cool for 10 minutes before cutting into 10 bars.