Matcha mousse cake

Instructions

1. Step 1

   Preheat the oven to 175°C, line the bottom of an 18 cm round cake pan with parchment paper and have a springform pan or ring of the same size ready for assembling. The thin sponge bakes quickly, so have all your equipment ready before you start whipping the eggs. The oven is ready once it has heated steadily for about fifteen minutes.

   Mark step 1 as done

2. Step 2

   Beat 100 g eggs with 50 g superfine sugar on high speed for about seven minutes, then lower the speed and beat for one more minute to refine the bubbles. Whole eggs need a long whipping, because they're the only thing that makes this sponge rise. The eggs are ready when they're pale cream in color, have tripled in volume and you can draw a figure eight on the surface.

   Suggested time: about 7 minutes.

   Mark step 2 as done

3. Step 3

   Sift 45 g cake flour and 5 g matcha powder together into the eggs and fold gently, then mix 15 g melted butter and 15 g warm whole milk with a spoonful of the batter and pour it back into the bowl. Sifting them together spreads the matcha evenly, so there are no dark green specks in the sponge. The batter is ready when it's an even pale green and still light and airy.

   Mark step 3 as done

4. Step 4

   Pour the batter into the pan, tap it gently to release air bubbles, then bake at 175°C for about 12 to 15 minutes. Moderate heat keeps the matcha green instead of turning yellow. The sponge is done when the top is dry, springs back when pressed and the edges pull slightly away from the pan.

   Bake at 175°C for about 12 to 15 minutes.

   Mark step 4 as done

5. Step 5

   Once the sponge has cooled, trim off the top and edges to leave a disk about one centimeter smaller than the springform pan, then set it in the center of the lined pan. The mousse will fill the gap around the sponge and cover its edges completely. The base is ready when it sits straight with an even gap all the way around.

   Mark step 5 as done

6. Step 6

   Sprinkle 8 g powdered gelatin over 40 g cold water and let it sit for five minutes. Gelatin needs to absorb water before it meets hot milk so it dissolves smoothly. It's ready when it has swollen into a clear, soft, jelly-like mass.

   Suggested time: about 5 minutes.

   Mark step 6 as done

7. Step 7

   Sift 10 g matcha powder and 30 g granulated sugar into 150 g whole milk, warm it over low heat and whisk until dissolved, then turn off the heat and stir in the gelatin and 100 g chopped white chocolate until completely melted. Mixing the sugar with the matcha first keeps the tea powder from clumping in the milk. The mixture is ready when it's smooth, glossy, evenly green and has cooled to room temperature.

   Low heat.

   Mark step 7 as done

8. Step 8

   Whip 300 g cold whipping cream for about three minutes to soft peaks. Moderately whipped cream gives the mousse a light, silky texture without making it fluffy like cotton. The cream is ready when the beater leaves clear trails and the peaks curl softly.

   Suggested time: about 3 minutes.

   Mark step 8 as done

9. Step 9

   Fold the whipped cream into the matcha mixture in two additions, pour it into the pan to cover the sponge completely and shake gently to level the top. A cooled matcha mixture keeps the cream from melting and the mousse from separating. The mousse is ready when it's an even jade green and has filled the gap around the sponge.

   Mark step 9 as done

10. Step 10

    Refrigerate the pan for about five hours, or overnight. A long enough chill lets the gelatin and white chocolate hold the cake's shape when you unmold it. The cake is ready when the top of the mousse is dry, firm and doesn't stick when touched.

    Suggested time: about 300 minutes.

    Mark step 10 as done

11. Step 11

    Warm the sides of the pan gently and remove the ring, then sift matcha powder (3 g) evenly over the top just before serving. Dusting at the last minute keeps the powder dry and fine instead of blotchy with moisture. The cake is finished when the top is evenly covered in fine green powder and the sides are smooth.

    Mark step 11 as done