Position a rack in the middle of the oven and preheat to 300
Lightly butter the bottom of a 9X2-inch round cake pan and line
the bottom with a round of parchment.
Lightly butter the parchment and the sides of the pan and dust
with cocoa. Tap out any excess cocoa.
Melt the chocolate and butter in a double boiler and let cool
With a stand mixer fitted with the whisk attachment, combine
the eggs, sugar, vanilla, salt and 2 Tbs. water.
Beat on medium-high speed until the mixture is very foamy,
pale in color, and doubled in volume, about 2 minutes.
Reduce the mixer speed to low and gradually pour in the
Increase the speed to medium high and continue beating untill
well blended, about 30 second.
Add the cocoa and mix on medium low just until blended, about
Pour the batter into the prepared pan.
Bake until a pick inserted in the center comes out looking wet
with small gooey clumps, 40-45 minutes.
Let cool in the pan on a rack for 30 minutes.
Cover the cake pan with a wire rack and invert. Remove the
pan and parchment and let the cake cool completely.
Transfer to a plate. Cover and refrigerate until very cold, at
least 6 hours or overnight.
Glaze the cake:
Melt the chocolate and butter in a double boiler.
Pour the wam glaze over the chilled cake and spread the glaze
evenly to within 1/4 inch of the edge.
Refrigerate the cake until the glaze is set, 20-40 minutes.
Before serving, remove the cake from the refrigerator and let it
come to room temperature, 20-30 minutes.
Cut the cake into small, if not tiny slices using a hot knife.