Preheat your oven to 170C (340F).
Line a 20x20 cm baking tray with baking parchment.
Melt your butter, sugar and golden syrup in a large pan over a low heat until the sugar has dissolved then remove from the heat and stir in the oats and all other ingredients.
Give the entire mixture a really good stir so that all of the oats are coated.
Pour the mixture into your lined baking tin and pat down with the back of a spoon.
Bake in the oven for 20 minutes. (The edges should be starting to brown but the middle should still be soft and wobbly.)
When the flapjack is cold, remove it from the tin and slice your flapjacks into 16 squares with a sharp knife.
