1 x 20cm round or 18cm square Christmas cake (see 'Goes well with', below)
4 tbsp raspberry or apricot jam, warmed and sieved
icing sugar, for dusting
500g pack marzipan
1.3kg ready-to-roll white icing
brown, green and red food colouring
9 whole cloves
black writing icing
Sit the cake on a large board or flat serving plate. Brush a little of the jam over the cake. Dust a clean surface with a little icing sugar, then roll out the marzipan until big enough to cover the cake (use string to help you measure). Carefully lift the marzipan onto the cake, pat down to cover smoothly and trim any excess off the bottom. Brush all over again with more jam.
Knead 1kg white icing until smooth, then roll out on an icing sugar-dusted surface until a little bigger than the marzipan size. Carefully lift onto the cake, partially pat down the sides to smooth and stick, allow the rest to stick in folds, or tease into shape with your fingers (step A). Trim any ragged edges.
For the robins, roll 3 walnut-size balls from some of the remaining white icing. Halve the icing that is left. Knead brown colouring into 1 half to give a rich colour, wrap well - this will be the branch. Divide the other half into 3 pieces, and colour 1 red, 1 pale brown and 1 green.
Re-dust the work surface, pinch off 3 marble-size balls of red icing and roll each into a teardrop shape for the breast. Use a cocktail stick to add texture, then stick 1 onto each robin - brush a little water onto the icing to help it stick. As you stick it, flatten the base of the ball slightly so that the robins stand up.
Divide the pale brown icing into 3 balls and roll each into an oval shape, then pinch 1 end of each into a gentle point (step B). Stick onto the robins so that the point is the head, and trim the tail if you need to. Poke a clove into each brown tip to make a little beak. Pull the round bit off the end of 6 cloves to leave spiky ends, and poke into robins to make feet. Use black writing icing to add eyes (step C).
Roll most of the dark brown icing into a long branch and attach to the cake with a little more water or jam. Roll smaller branches from the remaining dark brown icing. Pinch leaves from the green icing and attach. Add the robins and enjoy.