Preheat the oven to 160°C. Place the paper cake cases in a 12-hole bun tin.
Place the self-raising flour, reduced-fat spread, sweetener, sugar, baking powder, eggs and vanilla extract in a large mixing bowl.
Beat for 1-2 minutes with an electric whisk, until the whisk leaves a ribbon trail in the mixture. You can use a wooden spoon, but it will take more effort.
Spoon the mixture into the cake cases and place in the preheated oven for about 20 minutes, or until risen slightly and golden. A knife inserted into the cakes should come out clean when they are cooked.
Place the cakes on a cooling rack and leave to cool completely.
While the cakes are cooling, make the topping. Place the cream cheese and icing sugar in a small bowl and stir to mix completely until smooth.
Place the topping in a piping bag fitted with a small star nozzle. Pipe a small swirl of the topping in the middle of each cooled cupcake. Decorate each with a strawberry half, a blackberry, a blueberry, a raspberry and a quarter of a kiwi slice, placing on the topping. Serve.