Preheat oven to 180°C.

Cut both pastry in two parts. Riddle with holes and bake 3 pieces in between two baking tray for 18 to 20 minutes so they do not raise. Reserve. You can keep the last pastry to make some mini-tartelettes for your aperitif !

Pour milk in a saucepan. Seed vanilla. Add vanilla to the milk. Heat.

In the meantime, mix the 2 eggs and the egg yolk (reserve the white). Add flour.

When milk is warm, pour half of it together with the egg mixture. Stir, add the second half and mix again.

Heat again on low/medium stirring regularly until the cream thickens. Remove from the heat and add diced butter. Mix to melt butter and leave to cool.

Bring 1 dl. of water to a boil. Mix together with coffee and reserve.

Heat sugar with 3 teaspoons of water until it caramelises. Add warm coffee and stir constantly on low heat until you get an homogeneous mix. Refrigerate.

Cut up the pastry again so they have all the exact same size.

Cover the first one with pastry cream, add the second one on top and cover again with pastry cream. Add the last pastry.

Mix around 100 to 120 gr. of powdered sugar together with the egg white until you get the texture you are looking for. Ice the mille-feuille. Draw parallel lines with coffee extract. Use a pastry bag or a freezer bag with a little hole. Using the tip of a knife draw perpendicular lines so it looks like a Mille-feuille.