Heat the oven to 180C/160C fan/gas 4. Butter a 20cm x 30cm cake tin and line with two strips of baking parchment, leaving one strip overhanging to help you lift the sponge out once it is cooked. Beat all the sponge ingredients together in a large bowl using an electric whisk until combined, light and fluffy, about 2 mins. Scrape into the tin and smooth to the edges with a spatula. Bake for 25-30 mins until risen and golden. Check the cake is cooked by inserting a skewer into the centre – if there’s wet cake mixture on the skewer, return to the oven for 5 mins more, then check again. Leave to cool for 20 mins in the tin, then transfer to a wire rack to cool completely.

To make the icing, beat the butter and vanilla together in a large bowl using an electric whisk until smooth. Add half the sugar and beat well, then add the remaining sugar and the milk, and beat again until smooth. Put two-thirds of the icing in a bowl and mix in a drop of pink food colouring. Put the remaining third in another bowl and mix in a drop of purple food colouring.

Shape the green fondant into mini leaf shapes and press veins into them using a cocktail stick. Set aside.

Flip the sponge onto a plate or board and peel off the parchment. Put a large, curved star nozzle in a piping bag, then fill with the pink icing. Hold the bag directly above the cake and pipe a swirl in a clockwise motion, applying a steady pressure until you have a flower shape. Continue piping flowers over the sponge in a random arrangement until the pink icing has been used up.

Fill the piping bag with the purple icing (don’t worry about washing it first, any remaining pink icing will add a nice effect) and fill any gaps with more flowers or individual blobs of icing. When the cake is completely covered, poke the green fondant leaves in around the flowers. Cut into squares to serve. Will keep in a cool place in an airtight container for up to three days.