Directions

• For the coffee sweet pastry dough
• Cream the butter and confectioners’ sugar. Mix the egg with the espresso powder and stir in the butter mix with salt. Add the flours and knead until smooth. Wrap in plastic wrap and set aside in the refrigerator for at least an hour.
• Preheat the oven to 350 degrees Fahrenheit. Grease and line the bottom of a 10 inch tart pan with removable bottom with parchment paper. 
• Roll out the refrigerated dough to 1/2 inch thickness. Gently ease dough into the pan. Once the dough is fitted into the pan, trim the edge to the rim using a paring knife.
• Blind bake for about 15 minutes, remove the weights and continue baking for another 10/15 minutes, until it looks dry. Let it cool before umolding.
• For the milk chocolate ganache
• Bring the heavy cream to boil. Add the espresso powder the pour on top of the milk chocolate. Let it sit for a couple of minutes. Then whisk until smooth. Add the butter and mix well. Cover with plastic wrap, making sure that it touches the surface of the ganache. Let it cool.
• For the coffee chiffon cake
• Preheat the oven to 350 degrees Fahrenheit. Grease and line the bottom of a 9 inch baking pan. 
• In a medium bowl whisk together the oil, egg yolks and the first water (60 g/quarter cup). Add vanilla, glycerin and the rest of the water. Whisk until smooth.
• In a small bowl combine flour, baking powder and salt. Add the dry ingredients to the egg mixture, until the batter looks smooth.
• Start whipping the egg whites with cream of tartar in a medium bowl, until frothy. Then slowly add the sugar. Whip until soft peaks form. The meringue will look glossy
• Using a silicone spatula, fold the egg whites into the batter, making sure to to deflate it. Pour into the baking pan and bake for 25 to 30 minutes, until it springs back to the touch. Place a piece of parchment paper on your surface, and quickly place the cake upside-down on it. Leave it to cool. The cake will need to be cut diagonally in two once it’s cooled. You can freeze the other half for up to a month.
• For the coffee mousse
• Let the gelatin bloom with cold water. One bloomed, melt it in the microwave for 30 seconds. Heat the milk, then remove from the heat, add the espresso powder and the gelatin.
• Whip the heavy cream with mascarpone cheese, and the confectioner’s sugar. Once it starts getting thicker, add the milk mixture. Whip until barely stiff – pay attention not to overdo it. Place in a piping bag with a round tip.
• To assemble
• Place the molded tart crust onto a serving plate. Spread some of the milk chocolate ganache on its bottom, to create a 1/4 inch thick layer. Refrigerate to set.
• Place the chiffon cake in the middle, and continue to pour the ganache around the cake, until you reach the same level. Refrigerate again to set, and set the remaining ganache aside.
• Start piping blobs of coffee mousse over the cake. Once the cake is covered, add the rest of the mousse to the remaining ganache, and whip together. Place in another piping bag with a round tip, and place blobs all around the edge of the cake, over the layer of ganache. Dust with cocoa powder and serve.