How to Make It
Preheat the oven to 375°. Lightly butter and flour a 9-inch round cake pan.
In a heavy medium saucepan, combine the butter and chocolate. Melt over moderate heat, stirring frequently, until smooth, about 4 minutes. Remove from the heat and let cool slightly.
In a medium bowl, using an electric mixer, beat the eggs with the sugar at high speed until thick and pale, about 3 minutes. Add the flour and beat at low speed just until combined. Fold in one-third of the melted chocolate, then gently fold in the remaining chocolate; do not overmix.
Pour the batter into the prepared pan and bake for about 35 minutes, or until a toothpick stuck into the center comes out clean. Invert the cake onto a rack and let cool.
Meanwhile, in a saucepan, warm the cherry preserves over moderate heat. Cut the cake into wedges and serve with the cherry preserves and crème fraîche.