Pour the coffee into a measuring cup, add the butter, melt and leave to cool. Stir in the eggs.
Mix the flour and remaining ingredients in a bowl. Gradually stir in the coffee mixture. Transfer the cake batter to the prepared tin.
Approx. 55 mins. in the lower half of an oven preheated to 180°C. Remove from the oven, allow to cool slightly, remove from the tin and leave to cool on a rack.
Combine the quark and icing sugar. Using a sharp knife, cut into the cake diagonally towards the middle all around, starting approx. 1 cm from the edge. Remove the inner section. Spread the quark mixture over the cut surfaces of the cake, replace the inner section and press down gently. Dust the surface with icing sugar.