This cake balances the delicately sweet flavors of fresh blueberries and the subtle tang of crème fraîche. For added depth of flavor, the batter is infused with vanilla extract and perfumed with lemon zest. Using cake flour instead of all-purpose flour makes a more tender cake since it’s made from soft wheat, providing an ideal amount of protein and giving this cake the perfect structure. The result is wonderfully complex in both taste and texture.