Heat oven to 180C/160C fan/gas 4.
Make the first batch of sponges by
greasing and lining 2 x 20cm round tins.
Gently melt half the butter and chocolate
together in a saucepan. Mix half the flour,
sugar, cocoa, bicarb and ¼ tsp salt in
a large mixing bowl. Whizz one egg and
half the yogurt and beetroot in a food
processor or blender until fairly smooth.
Put the kettle on.
Tip the beetroot mix into the dry
ingredients along with the melted
chocolate mixture and 150ml boiling
water, then stir to combine. Stir in half
the food colouring, if using, and divide
the mixture between the tins. Bake for
25 mins until a skewer poked into the
centre comes out clean. Leave the cakes
on a wire rack to cool completely.
Repeat Steps 1 and 2 to make 2 more
sponges or if you're lucky enough to have
4 x 20cm sandwich tins you can bake in
a big batch all at once.
To make the frosting, briefly beat
together the soft cheese and butter,
then beat in the icing sugar and vanilla.
Use a little to sandwich the cooled
cakes together, then swirl the rest
all over the sandwiched cakes and
decorate with sweets, if you like. Sit
the cake somewhere cool (not the
fridge) to set a little before serving.