Melt the chocolate in a large heatproof bowl set over a medium-sized pan of barely simmering water, making sure the bottom of the bowl doesn't touch the water. Be careful not to overheat the chocolate or it will turn grainy and affect the finish of the cake.

While the chocolate is melting, put the whole egg(s), the egg yolks and Tate & Lyle Fairtrade Golden Caster Sugar in another large bowl. Beat with an electric hand whisk until thick and creamy. With a large metal spoon, quickly stir the melted chocolate into the egg mixture, along with the almonds and coffee, until well mixed.

In a scrupulously clean large bowl, beat the egg whites until stiff but not dry (see note, above, regarding egg whites for the largest cake). Using a large metal spoon, fold 1 heaped tablespoon of the egg whites into the chocolate mixture to loosen it. Quickly and carefully fold in the rest, using a figure of eight motion, until just combined.

Preheat the oven to 170°C/Fan150°, 325°F, Gas 3. Place a shallow dish or baking tin on the bottom shelf of the oven, then fill it with near-boiling water (it isn't safe to fill it before placing it on the shelf). The shelf for baking the cakes should be placed a third up from the bottom of the oven, just above the water.

Carefully pour the mixture into the prepared cake tin and lightly smooth over the surface, then place on a baking tray. Cover each of the 2 smaller cakes with a double thickness of parchment paper and make a hole in the centre of each the size of a 50p piece. Cover the 30cm (12”)cake with a double thickness of extra-wide foil with a hole made in it, as above.

Bake the 15cm (6”) cake for 55-65 minutes; the 23cm (9”) cake will take 75-85 minutes to bake and the 30cm (12”) cake will take about 2¾-3 hours.

The cake is ready when well-risen, with a nicely set crust, and when a fine metal skewer inserted into the middle comes out clean. Remove from the oven, take off the baking paper or foil, cover the cake with a damp, clean tea towel and leave to cool in the tin for 1 hour. Then turn it out on to a wire rack to cool completely, and remove the parchment paper.

Add the butter, bit by bit, stirring gently until melted. Remove from the heat and set aside to cool until the icing mixture has started to set to the consistency of double cream.

Meanwhile, if the tops of the cakes are uneven, trim with a sharp, long-bladed knife, then upturn on to wire racks so that there is a flat surface for icing. Brush away any loose crumbs and place flat plates or trays underneath each rack to catch any drips of icing.

Melt the apricot jam with the water in a small pan over a low heat, strain to remove any lumps and then, using a pastry brush, brush over the surface of the cakes to prevent any loose crumbs from spoiling the icing. Heat the jam again if it starts to thicken up too much.

Starting with the largest cake, pour over a thin layer of icing and then, using a long-bladed palette knife, quickly and evenly smooth it over the top and sides. Repeat with the remaining cakes and chill until set – about 30 minutes. If your fridge is not big enough, you will need to set them aside in a cool place instead and allow longer for the icing to set.

Put the remaining icing back over the pan of barely simmering water to melt again, then remove and allow to thicken, and, as before, give the cakes a second coat. Chill until the icing has set, then, if you have any spare icing, repeat the process for a third and final time and chill for about 1 hour. Any spare icing on the trays can be saved and used at the last minute to disguise any marks – just melt it, then pass it through a sieve into a small lidded container to remove any crumbs, and refrigerate.

When the icing has set, remove the cakes from the fridge and, using a small sharp knife dipped in very hot water, carefully cut them away from the cooling racks. Using the cake lifter carefully transfer each cake to a tray lined with baking paper and chill, uncovered, overnight or leave in a cool place.

The following day when you are ready to decorate the cake, place the largest cake on the cake board or stand and stack the other two tiers on top, in order of size, using the cake lifter and making sure they are evenly positioned. You can decorate the cake up to 6 hours ahead if you have adequate refrigeration or a very cool storage place.

Starting with the top tier, decorate the top of the cake with a few of the orchids. Next, work your way down to the lower tiers, arranging the flowers so that they point outwards. You may need to carefully push the stalks into the icing to secure them. The weather will determine how long in advance you can decorate the cake with the flowers, but if it’s cool they will probably be fine for 2-3 hours ahead.