Line a 12-section bun tray with paper cake cases. Put the butter, sugar, eggs, flour and baking powder in a bowl and beat with a hand-held electric whisk for about a minute until light and creamy. Divide the cake mixture between the paper cases and scatter with the semi-dried pineapple.
Bake in a preheated oven, 180°C (350°F), Gas Mark 4, for 20 minutes or until risen and just firm to the touch. Transfer to a wire rack to cool.
Spread each cake with a teaspoonful of the jam and then a thin layer of fromage frais.
Slice the fresh pineapple and mango. Cut rounds from the fruit flesh using a 2.5 cm (1 inch) cutter and arrange about 5 in a circle over each cake to make a flower shape. Place a raspberry, blackberry, cherry or grape in the centre of each, halving if large.