Make the crepes - Mix together the flour, salt and eggs. Gradually add in the milk, beating thoroughly to avoid lumps, then add the cherry juice. Rest the batter for 30 mins at room temperature.
Heat a crepe pan and brush with oil. Pour a ladle of batter into the pan and tilt to spread it around. When the top starts to look dry, carefully flip the pancake over. Cook for another 30 seconds then turn onto a plate while you cook the rest. You need 28 pancakes to assemble the cake.
Make the cherry filling - Put the water, sugar, cinnamon and frozen cherries into a large saucepan and warm through for a few minutes. Dissolve the cornflour in 50 millilitres of water and add to the pot. Cook for 5 more minutes, stirring often, until the sauce has thickened. Strain the cherries and put to one side to cool.
Make the sour cream filling - Mix together the sour cream, double cream and vanilla, then sieve in the icing sugar. Whisk to soft peaks.
Assemble the cake - Lay out one crepe and spread a thin layer of sour cream filling onto it. Put a line of cherries across the middle then roll it up like a cigar. Repeat with the rest.
Lay out 7 pancakes onto your serving plate. Brush with sour cream filling then position 6 pancakes on top. Brush with more filling, then lay out 5 pancakes, followed by a layer of 4, 3, 2 then 1 pancake on top. Cover both sides of the pancake stack in the rest of the sour cream filling and use a palette knife to smooth it out.
Add a few drops of pink food colouring to the desiccated coconut and mix it through. Cover the sides of the cake in coconut. Chill for 4 hours, or overnight, then use a sharp knife to cut slices and serve.