For the countertop:
In a bowl, mix the egg whites with the salt until they double in volume, add the sugar, little by little and mix until you get a shiny and firm meringue.
Separately, melt the chocolate with the butter on a steam bath, then set aside to cool.
Meanwhile, sift the flour with the baking powder and add them over the egg white meringue, stirring with a spatula from the bottom up, and at the end we pour the melted chocolate into a thin thread and mix.
Pour the resulting composition into a rectangular tray lined with baking paper and bake the cake for 40 minutes at 170 ° C.
Heat water, sugar and rum in a kettle until it boils, then set aside and let it cool.
For the cream:
In a large kettle, put the milk on the fire together with the bag of pudding, the sugar and a little vanilla essence. Stir continuously until it begins to thicken.
Turn off the heat and let it cool completely, stirring occasionally so as not to form a crust on top.
When the cream has cooled well, we mix the whipped cream with the powdered sugar until it becomes firm, then with a spoon we put the cooled cream, always mixing until we incorporate everything well and we obtain a fine and homogeneous cream.
On a tray, place the top, syrup well and pour over the vanilla cream, level nicely, sprinkle all over the surface grated chocolate and let cool until ready to serve!