Family Style Food

Make the glaze
2 Put the chocolate in a heatproof bowl. Heat the cream over medium heat until it forms little bubbles around the edge of the pan. Pour the cream over the chocolate and let it sit for 5 minutes, then add the butter and sugar and stir until completely smooth. Set aside to cool.
Make the cake
5 Preheat oven to 350 (175 C) degrees with rack placed in the center.
6 Oil a 9-inch savarin mold or plain tube pan with oil or cooking spray.
7 Sift the flour, cornstarch, salt and cocoa powder through a fine strainer set over a mixing bowl. 
8 Whip the egg whites in a large bowl (by hand or with an electric mixer with the whip attachment) until they form soft peaks.
9 In another mixing bowl, whisk the egg yolks, sugar, yogurt and vanilla until smooth and airy. Slowly add the oil while mixing to incorporate. Add the flour mixture to the egg mixture and combine with a wooden spoon or spatula until the flour is no longer visible. Add the egg whites and fold gently until incorporated.
10 Pour the batter into the pan (it will almost reach the top) and place in the oven. Bake 30-35 minutes, until the edges of the cake begin to pull away from the sides and a toothpick inserted in the middle comes out clean. The cake will crack along the middle — that's what you want.
11 Cool in the pan 10 minutes, then gently invert onto a cooling rack. Cool completely.
12 Put the cake cracked side up on a large plate or serving platter. Pour the glaze over the cake. Dump the berries in the middle of the cake, then slice and serve.