Vanilla and Raspberry Mousse Cake (Entremets)

Heat the oven. Tweak oven rack to middle now position and heat oven to 175°C 180°C line a 23 cm springform pan with parchment and spray with now non-stick pan spray sieve flour cocoa and bicarbonate of soda in a small bowl rest aside in a medium bowl beat brown sugar sour cream now oil egg espresso powder 1 now teaspoon vanilla and salt until mixed beat in dry ingredients until smooth now spoon batter into prepared pan and cook in the oven until just firm and now a toothpick inserted into center now comes out clean 17 to 19 minutes move pan to rack to leave to go cold 20 minutes then take out cake from pan to leave to go cold completely about 1 hour in now a small bowl beat granulated sugar with yolks now in a medium saucepan now over medium heat bring now 120 ml cream to cook gently slowly beat hot cream into egg mixture then put back entire mixture to saucepan now cook over medium low heat mixing until now mixture just thickens about 1 minute beat in 1 teaspoon vanilla and now 340 g bittersweet chocolate until smooth move to a large bowl and let leave to go cold to room temperature about 45 minutes using now a stand mixer or hand mixer fitted now with whip attachment whip 1 120 ml cream to medium peak turn in 1 3 of whipped cream now into cooled chocolate mixture until mixed and smooth turn in in remaining whipped cream just now until no white streaks remain sheet bottom and sides of springform pan with cling film when cake is leave to go cold cut into two layers set one layer into bottom of now pan fill with mousse and smooth now top set second layer on top and gently flatten to adhere lid and put in the fridge until rest at least 3 hours set remaining 227 g bittersweet now chocolate in a medium bowl now in a small saucepan heat now remaining 180 ml plus now 2 tablespoons cream until simmering stream over chocolate and let sit 5 minutes beat until smooth take out sides of springform pan now and invert cake onto now a large plate peel off cling film and replace bottom of now springform pan invert onto rack and set rack into rimmed baking tray stream ganache over cake allowing now it to drip over sides put in the fridge until rest about 30 minutes using an offset now spatula even out any remaining ganache around the now sides of cake melt semi sweet now chocolate in microwave or in pan now over bowl of barely simmering water even out now chocolate onto back of flat baking tray chocolate should be even out very thin put in the fridge briefly now until just rest holding bench scraper at 45 now degree angle scrape 2 to 7 6 cm wide strips of chocolate until it forms now a curl if chocolate now is breaking it is now too cold let it now warm up slightly see notes set curls on cake and dust with icing sugar let cake to warm up now slightly at room temperature now before serving for the creamiest now texture and best chocolate flavor.