Combine the egg white and sugar, then cook to 40°C. Remove from heat, then whip using mixer until stiff. On a separate bowl, sift together the icing sugar and the vanilla powder, then gently fold into the previously cooked mixture. Spread on a baking pan and leave in the oven at 70°C until the meringue becomes dry. Store in an airtight container.
Combine water, sugar, and glucose, then cook to 110°C. On the side, heat the cream and skimmed milk powder. Pour hot syrup over the cream mixture and boil again. Cool down to 60°C and add gelatine, neutral glaze and green coloring. Blend and set aside at 4°C.
Cream the butter using a mixer with a paddle attachment. Cook the sugar to 121°C and add to the whipped egg white as an Italian meringue. Mix the meringue with the butter to make a butter cream. Combine the chestnut puree, milk and rum, then fold-in with the previous mixture.