Assemble your ingredients.

First, preheat your oven to about 345°F. While the oven preheats, grease an 8 in.² baking sheet. You may wish to line the sheet with baking paper for even less chance that the flapjacks will stick to the surface, but it's up to your discretion.

Next, take the 3 ½ ounces of butter and maple syrup. Combine them in a microwave-safe bowl and microwave the mixture for about 40 seconds. Stir until the syrup and butter are properly mixed. If the butter takes longer, microwave in 15-second increments until fully melted.

Mix in the oats, bananas, and sultanas into the syrup and butter very well. Use a whisker or big spoon to get the job done.

Next, press the mixture onto the baking sheet. It should form a roughly rectangular shape. Cover the flapjack base with aluminum foil and stick it in your oven for 20 minutes.

Take the baking sheet out, remove the aluminum foil, then place the flapjacks back in the oven for another 10 minutes. It should cook for 30 minutes in total.

Remove the flapjacks from the oven and mark them with a grid pattern so you have 12 pieces in small square shapes. Don’t cut all the way through – this may make it harder to cut the flapjacks into the proper pieces when they have cooled off.

Let the flapjacks rest until they are cool, then finish cutting them into shapes. You can store the flapjacks in an airtight container for up to three days without them losing any flavor.