-
Butter a 20 cm springform pan and line the bottom with parchment paper. Preheat the oven to 180°C.
-
In a large bowl set over a pan of barely simmering water, melt the chocolate, stirring as little as possible.
-
Turn off the heat but leave the bowl over the warm water. Pour in the hot espresso and stir.
-
Then add the butter pieces and press them into the chocolate gently. Allow the butter to soften without stirring.
-
Sift together the flour, cocoa powder, and baking powder in a separate bowl. Remove the bowl of chocolate from the heat and stir until the butter is melted. Let sit for a few minutes to cool, then stir the egg yolks together and briskly stir them into the melted chocolate mixture.
-
Fold in the pureed beets.
-
In a stand mixer whip the egg whites with a pinch of salt until stiff. Gradually fold the sugar into the whipped egg whites with a spatula, then fold them into the melted chocolate mixture, being careful not to overmix.
-
Fold in the flour and cocoa powder.
-
Scrape the batter into the prepared cake pan and reduce the heat of the oven to 160°C.
-
Bake the cake for 40 minutes, or until the sides are just set but the center is still is just a bit wobbly. Do not over bake.
-
Let cake cool completely, then remove it from the pan.
-
Serve cake with a dollop of whipped cream or mascarpone cheese and a sliver of candied beets!