Preheat the oven to 180°C (160°C Fan/Gas Mark 4). Grease and line an 10” x 8” rectangular baking tin.
Place the sugar, butter and golden syrup in a saucepan and heat gently whilst stirring until melted together.
Remove from the heat and mix in the oats. Press into the prepared tin and bake for 25-30 minutes until lightly golden and bubbling.
Leave the flapjack to cool in the tin. Once cooled remove from the tin.
Break the chocolate into pieces and place in a microwavable bowl. Melt the chocolate in the microwave, in 30 second bursts stirring between each burst until the chocolate is melted.
Using a spoon, drizzle the melted chocolate over the flapjack and leave to set for a few minutes.
Cut the flapjack into 12 pieces and enjoy!