Dark Side of Spring – Blueberry Chocolate Mousse Cake

Brownie Cake Base

1. Adjust oven rack to middle position and heat oven to 325℉. Butter bottom and sides of 9-1/2-inch springform pan. Melt butter, chocolate, and espresso powder in large heatproof bowl set over medium saucepan filled with 1 inch of barely simmering water, stirring occasionally until smooth. Remove from heat and cool mixture slightly, about 5 minutes. Whisk in vanilla and egg yolks; set aside.

2. In stand mixer fitted with whisk attachment, beat egg whites and salt at medium speed until frothy, about 30 seconds. With machine running slowly add brown sugar until combined, about 30 seconds. Increase speed to high and beat to soft peaks (when whisk is lifted), about 1 minute, scraping down sides halfway through. Using whisk, fold one-third of beaten egg whites into chocolate mixture to lighten. Using rubber spatula, fold in remaining egg whites until no white streaks remain. Carefully transfer batter to prepared springform pan, gently smoothing top with offset spatula.

3. Bake until cake has risen, firm around edges, and center has just set but is still soft (center of cake will spring back after pressing gently with finger), 15-18 minutes. Transfer cake to wire rack to cool completely, about 1 hour. (Cake will collapse as it cools.) Do not remove cake from pan.

4. Remove side of cake pan and press an 8-inch, (3-inch high) ring mold to trim cake, set aside.

Note: You can omit Step 4 and pour chocolate mousse over the base. However, the base will not be visible in the final presentation.

Chocolate Mousse

1. Combine cocoa powder and hot water in small bowl, set aside. Melt chocolate in large heatproof bowl set over medium saucepan filled with 1 inch of barely simmering water, stirring occasionally until smooth. Remove from heat and cool slightly, about 5 minutes.

2. In clean bowl of stand mixer fitted with whisk attachment, whip cream, granulated sugar, and salt at medium speed until mixture begins to thicken, about 30 seconds. Increase speed to high and whip until soft peaks form when whisk is lifted, about one minute.

3. Whisk cocoa powder mixture into melted chocolate until smooth. Using whisk, fold one-third of whipped cream into chocolate mixture to lighten. Using rubber spatula, fold in remaining whipped cream until no white streaks remain. Spoon mousse into prepared brownie base carefully and gently tap pan to remove any large air bubbles; gently smooth top with offset spatula. Wipe inside edge of pan with damp cloth to remove any drips if necessary. Refrigerate cake at least 15 minutes while preparing blueberry mousse.

Blueberry Mousse

1. In small bowl, sprinkle gelatin over water; let stand at least 5 minutes. Place white chocolate in medium bowl. In a small saucepan, whisk together 1/2 cup cream, salt  and blueberry powder and bring to simmer over medium-high heat. Remove from heat; add gelatin mixture and stir until fully dissolved. Pour cream mixture over white chocolate and whisk until chocolate is melted and mixture is smooth. Cool to room temperature, stirring occasionally, about 5 minutes (mixture will thicken slightly).

2. In clean bowl of stand mixer fitted with whisk attachment, whip remaining 1 cup of cream at medium speed until it begins to thicken, about 30 seconds. Increase speed to high and whip until soft peaks form when whisk is lifted, 15 to 60 seconds. Using whisk, fold one-third of whipped cream into blueberry mixture to lighten. Using rubber spatula, fold remaining whipped cream into white chocolate mixture until no white streaks remain. Spoon blueberry mousse into pan over middle layer. Smooth top with offset spatula. Return cake to refrigerator and chill until set, at least 3 hours.

Assembly

1. Place chocolate in a medium bowl, set aside. Bring cream, corn syrup and salt to a full simmer over medium heat in a small saucepan. Remove from heat and pour hot cream over chocolate; let stand for 3 minutes, add vanilla and whisk until smooth. Cool chocolate until slightly thickened, about 3-5 minutes.

2. Drizzle chocolate around the edge and allow it to drip down the side of cake. Spread remaining on top. Let chocolate set for 5 minutes and decorate top with berries.