Matcha Mousse Cake

Matcha Sponge

• Preheat oven to 175C / 350F (without fan assistance). Line the bottom of 2 5-inch cake tins with parchment paper, leaving the cake tins ungreased. Set aside.
• Sift plain flour, corn flour and matcha powder together thrice. Set aside.
• Place butter and milk in a medium mixing bowl and melt them over a pot of simmering water or in a microwave (microwave at full power for 30 seconds. Give the mixture a stir, then microwave for 10 seconds, check the mixture and repeat until butter has melted). Set aside.
• Heat a small pot of water and place a large mixing bowl of over - the bowl should fit snugly on top of the pot and the bottom of the bowl should be 1 inch away from the water surface. Remove the mixing bowl from the pot. Bring the water to a boil then turn the heat down to a simmer.
• In the large mixing bowl, add in eggs and sugar. Whisk immediately with a wire whisk to mix them together. Place the mixing bowl over the pot of simmering water and whisk constantly until the mixture is warm like baby's milk (or until the sugar has melted). Remove the mixing bowl from the pot. You can turn off the heat as you don't need the pot of water anymore.
• Change to an electric mixer and whisk the egg and sugar mixture on medium-high speed until thick and ribbony. This will take about 5 minutes. You should be able to draw an infinity symbol with the batter before the batter slowly sinks back into itself. Turn the electric mixer speed to low and beat for 1 minute to even out the air bubbles.
• Sift in ½ of the flour mixture and fold in with a rubber spatula until incorporated (never use an electric mixer for this step). Sift in the remaining flour mixture and fold until incorporated.
• Pour ⅓ of the batter into the butter-milk mixture and fold until the butter-milk has been incorporated. Pour it back into the large mixing bowl and mix until the batter is homogenous.
• Divide the batter between the 2 cake tins. Drop the cake tin once on the tabletop to remove excess air bubbles. Bake in the middle shelf for 18 to 20 minutes until a skewer inserted into the center comes out clean and the top of the cake springs back when touched lightly.
• Cool the cake in their tins completely on a wire rack before using. Run a thin spatula along the edges of the cake and invert them out.

Matcha Mousse

• Whisk 1 tablespoon water and matcha together in a small bowl. Set aside.
• Place 2 tablespoons water in a small heatproof bowl. Sprinkle in the gelatin and set aside for 5 minutes. Place the bowl of gelatin in a pan of simmering water and heat until the gelatin has dissolved. Remove from heat and set aside.
• Whisk egg yolks, sugar and salt in a medium mixing bowl with a wire whisk. Place milk and 75 grams of cream in a small pot. Heat over medium heat until the milk mixture starts to simmer. Drizzle in the milk mixture bit by bit, while whisking the egg yolks mixture constantly, tempering the egg yolks. When more than 1/4 of the milk mixture has been added, drizzle in the milk mixture in a tiny stream, whisking the egg yolks mixture constantly, until all the milk mixture has been added. (To prevent your mixing bowl from sliding around on the tabletop, place the mixing bowl on top of a damp tea towel or table cloth.)
• Pour the egg and milk mixture back into the pot. Cook over medium heat until the mixture has thickened (do not let it come to a boil), stirring constantly. You will know it's done when the mixture can coat the back of a spoon / spatula, and when you draw a line on the back of the spoon / spatula, the line will not disappear so easily. Remove from heat immediately then stir in the gelatin mixture and matcha mixture. Strain the mixture through a sieve into a small bowl. Press a plastic wrap directly onto the surface of the custard and set aside to cool completely.
• After the custard has cooled completely, chill a metal bowl and the beaters of an electric mixer in the refrigerator for 15 minutes.
• Remove the chilled bowl and beaters from the refrigerator and add in the 125 grams of cream. Whip the cream over high speed until soft peaks are formed.
• Peel off the plastic wrap on the custard and discard. Fold in 1/4 of the soft cream to lighten the mixture. Pour the lightened custard back into the cream and fold until the mixture is homegenous. Use immediately.

Assembly

• Cake Ring: Place a 5-inch or 6-inch cake ring (at least 3-inches tall) on a cake board and place 1 cake layer in the middle. Pour in half of the mousse and spread evenly. Place the second cake layer in the middle and pour in the rest of the mousse. Chill for at least 4 hours or overnight until set.
• Cake Tin: Line two 5-inch cake tins with plastic wrap, making sure the plastic wrap overhang so that you can lift out the cake layers later. Place the cake layers in each of the cake tins and divide the mousse between the 2 tins. Chill for at least 4 hours or overnight until set.

Serve

• Cake Ring: Wipe the exterior of the cake ring with a hot tea towel to loosen the cake. Remove the cake ring, garnish with Sesame Brittle (recipe below) and serve.
• Cake Tin: Use the plastic wrap overhang to lift out the cake. Place one layer on the cake board. Dip a metal spatula in boiling water, wipe dry with tea towel or paper towel and smooth the top of the mousse. The aim is to melt some of the mousse on top so that the cake layers will stick together. Repeat the dipping, drying and smoothing for a few minutes until you can see that the top of the mousse is slightly melted. Place the second cake layer on top. If the edges / top of the mousse is uneven, use the dipping-drying-smoothing method to smooth out the mousse. Chill the cake again for about 30 minutes to 1 hour. Garnish with Sesame Brittle (recipe below) and serve.

• Preheat oven to 175C / 350F (with or without fan assistance is fine). Toast the black and white sesame seeds for 5 to 10 minutes until fragrant. Alternative, toast them in a small frying pan until fragrant. Remove from heat and set aside to cool completely.
• Turn over a baking sheet (minimum 9-inch big) and place a baking parchment or silpat on top. Lightly oil the baking parchment or silpat. Set aside.
• Place sugar in a small pot. Add in water. Do not stir. Place the pot over medium heat and heat until the sugar has dissolved, swirling the pan occasionally. Allow the mixture to boil and bubble for 5 minutes, until it turns a light amber colour - do not stir the mixture!
• Once the caramel is light amber in colour, remove from heat and working quickly, stir in the butter with a silicone spatula until mixture is smooth and any frothing has subsided. Stir in the sesame seeds and immediately pour the mixture onto the baking parchment / silpat, spreading it out as thinly as possible.
• Let the brittle cool and harden completely, then break into small pieces. Store them in an airtight container at room temperature.