Preheat the oven to 180ºc / Gas 4. Line a 20.5cm (8in) square tin with baking paper.
Place the butter, sugar and golden syrup in a pan and heat gently until the sugar dissolves, stirring all the time.
Add the oats and raisins to the pan and mix well. Remove from the heat and spread into the tin, pressing down well with a back of a spoon. Bake for 15-20mins until golden brown and firm. Set aside to cool and leave in the tin.
Place the chocolate and butter in a heatproof bowl over a pan of simmering water to melt, stirring occasionally. Cool slightly then add the cream. Spoon over the flapjack and leave to set. Top tip: when you add the cream, if it cools the chocolate down and doesn't seem to combine, place the bowl back over the pan of hot water and warm up slightly.
When the chocolate has set, lift the flapjack out the tin, using the lining paper to help you. Cut into squares with a sharp knife and then enjoy....
