Melt the butter and golden syrup in a pan over a low heat. Remove from the heat and mix in the oats, sugar and fruit. Stir everything together.
Grease a 23 cm (9 inch) square and 6 cm (2½ inch) deep tin. Turn the mixture into the tin and press down with the back of a spoon. Bake in a preheated oven, 190°C (375°F), Gas Mark 5, for 25–30 minutes until golden and firm. Cool.
Melt the chocolate in a bowl over a pan of simmering water (see