Preheat the oven to 160?C, fan 140?C, gas 3. Grease and line the base of a 30 x 20cm (8 x 12in) roasting tin.
Using scissors, cut the apricots into very small pieces. Put the apricots and sultanas in a saucepan, cover with the orange juice and bring to the boil. Reduce the heat slightly and cook for 15 mins or until all the juice has been absorbed by the dried fruit.
Add the butter to the fruit and stir gently over a low heat until the butter has melted. Remove from the heat and leave to cool slightly.
Crack the eggs into a bowl, add the sugar and vanilla extract and whisk together. Add the plump dried fruit, flour and baking powder to the egg mixture and mix thoroughly. Pour into the tin.
Bake for 40 mins – you may need to cover the top with baking parchment to stop it from going too brown and then bake for another 15-20 mins.
Leave in the tin to cool slightly and then cut into about 24 squares. Dust with icing sugar.