Put the butter and sugar in a medium bowl and beat together until light and creamy. Beat in the egg yolk, vanilla extract and flour until the mixture forms a dough. Knead until smooth, then wrap in cling film and chill in the fridge for 30 minutes.
Preheat the oven to 180ºC/fan 160ºC/gas mark 4. Roll the dough out on a lightly floured surface to a thickness of 3mm. Stamp out 10 cookies and put on a non-stick baking tray. Stamp out 20 heart and 20 teardrop shapes, re-rolling the trimmings as you go. Put them on another baking tray in pairs so the straight sides of the teardrop and heart touch – the teardrop forms the bee body and the heart is the wings. Bake the biscuits for 5-8 minutes until golden. Transfer to a wire rack to cool.
Put the icing sugar in a bowl and stir in 3-4 tsp cold water until the icing is a thick pouring consistency. Spread the icing on to the round biscuits and the wings of the bees. Mix a few drops of yellow food colouring into the remaining icing and ice the bodies of the bees. While the icing is still tacky, decorate the round biscuits using the jelly beans as petals. When the icing on the bees is dry, use the black writing icing to add stripes, eyes and wing details.