Sable breton tartlets with pistachio mousse & chocolate ganache

The calculation in the recipe is for four 8cm (3.15 inch) tartlets.

• Grind soft butter with powdered sugar and salt until smooth.
• Add an egg at room temperature, and then the cream. Stir after each ingredient.
• Add the flour and baking powder, and knead the dough (it should turn out thick, but the consistency is closer to sponge batter, and not to shortcrust pastry).
• Pour the dough about 1.5cm (0.60 inch) high into perforated rings installed on a perforated mat, and refrigerate for 2 hours.
• Bake the blanks at 329F (165C) for 25 minutes until golden brown.
• Remove the Sable Breton from the tins while it is still soft. After cooling, it will become like cookies.

• Heat the cream until hot, pour it over the chocolate, and let it melt completely.
• Punch the mass with a blender, and let it stabilize for 6-8 hours in the fridge (no need to whip the ganache).

• Pour the gelatin with cold water, and let it swell.
• Bring the milk to a hot state, pour it over white chocolate and pistachio paste, and mix until smooth.
• Dissolve the gelatin (10 seconds in the microwave) and add it to the chocolate-milk mixture.
• In a separate bowl, whip the cream to soft peaks.
• Add the chocolate-milk mixture to the cream, and combine.
• Fill the "Donut" molds with mousse, and freeze.

• Put a layer of chocolate ganache on the Sable Breton.
• Cover the mousse part with chocolate velor (50/50 white chocolate and cocoa butter, a little green matcha), and put these blanks on top of the ganache.
• Add some pistachio paste to the grooves, as in the photo.
• Decorate the sides of the cakes with a chocolate side or ground pistachios.