1 lb sugar
4 oz cocoa powder
1 lb flour
2 tsp baking soda
1 tsp baking powder
2 c buttermilk
2 c creme fraiche
8 oz butter, melted
6 eggs
1/3 c rum
1 recipe chestnut cream or hazelnut cream
1 recipe chocolate buttercream
Prepare the nut cream and chocolate buttercream the day before. Grease a 15×10- inch jelly roll pan and line with waxed paper. Siftt all the dry ingredients together. Whisk in the buttermilk and creme fraiche, then the butter and the eggs. Spread batter evenly in a 15×10-inch jelly roll pan, and bake at 350 for 15-20 minutes.
Sift 3-4 T powdered sugar in a 15×10- inch rectangle on a cotton tea towel. When the cake is done, immediately loosen from sides of pan, and turn out onto sugared towel. Peel off waxed paper. Roll up cake and towel together, from the shorter edge, and cool completely on a wire rack, seam side down.
To assemble the cake: carefully unroll cake and brush with rum. Spread the nut cream evenly over the cake and roll back up. Place on a serving platter. Frost with chocolate buttercream. Slice diagonally to serve.