Melt the butter in a saucepan
Peel the beetroot and blend it in a blender with the melted butter
In a bowl, mix beetroot-butter, sugar, cocoa, and vanilla.
Add the eggs on at a time - whisk thoroughly
Add the flour and whisk till the dough as an even texture
Lubricate the springform pan with some butter and pour the dough into the pan
Bake the cake at 175 degrees C for 30-40 min
Let cool completely on the kitchen table