Preheat the oven to Gas Mark 4, 180°C, fan 160°C. Grease a 20cm (8in) square baking tin with butter and line the base with nonstick baking paper.
Place the syrup, sugar, butter and peanut butter in a pan and melt over a low heat, stirring, until everything is combined. Add the oats and dates, and stir again until everything is well coated. Press the mixture into the prepared tin with the back of a spoon, ensuring it is well evenly packed into the tin.
Bake in the preheated oven for 20 minutes, until golden.
Remove from the oven and cut into flapjacks using a sharp knife. Leave to cool completely in the tin, otherwise the flapjacks will be flaky and fall apart.
You can also use pure sunflower spread in place of the butter to make these flapjacks dairy-free.
*Inspired by Deanne J. featured in the Realfood Cookbook