First wash your vehicles in warm soapy water and dry thoroughly.  I bought new vehicles especially for use on the cake - they made a much appreciated extra little present for the birthday boy!

Place your cake on a plate or cake board.  If using a homemade cake, stack up any layers with a little icing in between.

With the tip of a sharp knife, cut a hole in the top of the cake and remove the resulting chunk of cake. Eat it up before anyone else snaffles it - it's the cooks reward!

Spread your icing over the top of the cake, leaving the hole bare. Arrange the construction vehicles so that they look like they are in action - being sure to place a digger by the hole. Add the chocolate chips and chocolate chunks to complete the picture.  I had the bulldozer shovelling dark chocolate chips, and piled a few chunks of dark chocolate into the tipper truck.