Butter and line 3 x 15 or 16cm round tins (alternatively do the baking in batches if you only have one tin). Heat the oven to 170C/150C fan/gas 3.

Gently melt the chocolate, butter and sugar together in a large microwave-safe bowl on medium heat for a minute at a time, stirring until melted or, set a bowl over a pan of simmering water. Leave to cool a little.

Beat together the eggs with the vanilla and soured cream in a bowl. Sift the flour, cocoa and baking powder into another bowl and whisk to distribute. Stir the egg mix into the cooled melted chocolate, then fold in the flour mix and fold through until all the powder has disappeared.

Spoon a third of the mixture into each tin (if you weigh the tins, you can get it perfectly even and your cakes will cook at the same rate and to the same height). Level off each thin layer with the back of a spoon.

Bake until just cooked, so when a skewer poked into the centre of the sponge layer comes out with a few crumbs and the cakes are shrinking away from the tin a bit. This will take about 25-30 mins, but check after 20 to be safe as all ovens vary. Remove and cool in the tins on a wire rack, or on top of cold oven hob rings.

Meanwhile, to make the ganache, microwave all the ingredients together in 30 sec bursts until they have all melted, stirring at each interval. Or melt everything together in a bowl set over a pan of simmering water. Cool to room temperature before adding to the buttercream.

To make the buttercream, beat the butter and vanilla paste until pale and creamy. Gradually add the icing sugar, beating well between each addition. (Using unrefined sugar will give the buttercream a natural caramel flavour.) Beat in the cooled ganache.

To make the antlers, combine the sugar and butter with the vanilla paste until amalgamated but not creamed. Add the egg and combine. Mix the flour with the spices then tip that in and mix to form a dough. Wrap in cling film and chill in the fridge to firm up for 20 minutes. Roll out on a floured surface to a 5/6mm thickness. Lay the template on the dough and cut around it using a small sharp knife – make two sets in case of breakages (any additional dough can be saved). Push the lolly sticks up into the bottom of the antlers and bake for around 15-20 mins until cooked through and golden. Allow to cool.

Make the ears by pulling a little of the brown fondant icing off the block and kneading it with white fondant icing to make a pale brown. Roll the rest of the dark brown icing out thickly on a surface dusted with icing sugar. Roll the paler icing out thinly. Cut large teardrop shapes from the lighter icing to form the ears (about 6cm in size) and stick the lighter shape on top of the darker icing with a little water. Cut a larger teardrop around the lighter shape. Fold and pinch together at the base, push a cocktail stick into the bottom of each one and set aside to firm up.

Trim the cakes flat if they have a little hump where they have been baked. Put the first layer onto a 16cm cake board and use a little of the chocolate frosting to secure it to the board. Spread frosting over the first layer then add layer two. Sandwich together by pressing gently and add another layer of frosting to this layer. For the last layer, take the sponge and invert it on top of the other two cakes, so that the smooth part of the cake – that was on the bottom of the tin –becomes the top. This will make it nice and neat. Spread a very thin layer of icing over the whole cake to crumb coat it and chill to set for about 30 mins.

Add more buttercream to the cake to make a clean top coat – use a palette knife or side scraper to get a smooth finish (but do save a little of the buttercream for the final flourish). Mark out the eyes with a cutter so you can see where to add them. Roll little strips of black fondant icing for the eyes and lashes, then stick these onto the cake. Mould the nose with red fondant icing and stick it on with a cocktail stick, pushing one end into the nose and the other into the cake.

For the little collar, roll out about 100g of green fondant icing on a surface dusted with icing sugar and cut a thin strip for the bow that will fit around the base of the cake. Stick the ends together with a little water, then make a bow by folding another thin strip and stick this onto the collar with another dab of water. Scoop the leftover buttercream into a bag with a large star nozzle. Pipe some fluffy reindeer hair on top of the cake, then add the ears and biscuit antlers, pushing them in gently but firmly.