In medium bowl, sift together flour, baking powder and salt; set aside.
In large bowl, beat butter and sugar with electric mixer until light and fluffy; add eggs and vanilla; beat well. Add flour mixture to butter mixture; alternating between adding butter mixture and milk; beat well after each addition. Divide batter evenly into cake pans.
Bake 38-40 minutes, or until toothpick inserted in center of cake comes out clean. Cool 10 minutes in pan; remove to cooling grid and cool completely before assembling.
In large bowl, whip cream, crème fraiche and confectioners? sugar into soft peaks. Add 1/2 jar of lemon curd and whip until incorporated.
To assemble, cut each cake layer horizontally into 2 thinner layers. Place first layer on serving plate. Spread with 1/4 of remaining lemon curd. Top with 1/4 of lemon whipped cream. Scatter with 1/4 of blueberries. Repeat with remaining cake layers, lemon curd, lemon whipped cream and blueberries. Refrigerate until ready to serve.