Step 1

Heat the oven to 180C/fan 160C/gas Butter and line the base of a deep 23cm springform tin with baking paper.

Step 2

Melt the butter and chocolate together in a bowl set over but not touching a pan of gently simmering water. Take off the heat and cool a little.

Step 3

Put the beetroot in a food processor or high-speed blender and whizz to a purée. Add the eggs and sugar, and whizz again.

Step 4

Put the flour and cocoa powder in a bowl and mix together. Stir in the beetroot purée, then the chocolate-butter mixture until you have a uniform batter. Scoop into the tin and level out. Bake for 40-45 minutes or until risen.

Step 5

Leave to cool in the tin for 20 minutes then unclip and leave to cool completely. Transfer to a serving plate and serve with a dollop of crème fraîche, if you like.