A classic genoise cake is elevated for summer with fresh mixed berries and lemon zest folded into a tangy whipped creme fraiche and rolled for a fun and refreshing dessert.
Over a double boiler, combine eggs and sugar and whisk until egg mixture reaches 105-113 degrees Fahrenheit.
Using a mixing bowl with a whisk attachment, pour egg and sugar mixture into bowl and beat on medium speed with whisk for 12-15 minutes, or until cool.
Reserve 1/8 of egg mix and gently mix in melted butter and vanilla extract.
Using a fine strainer or flour sifter, sift cake flour, in batches, over the egg mix and gently fold in until all flour has been incorporated into egg. Then gently re-incorporate the small egg mix with the butter and vanilla into the flour egg mix.
Preheat the oven to 425 degrees and line a large baking sheet with parchment paper. Pour cake batter into lined pan and bake for 8 minutes.
Pull baked cake from oven and let cool on a wire rack.
Remove cake from sheet pan and allow to cool completely.
In a mixing bowl with a whisk attachment, combine heavy cream, sour cream, and powdered sugar and whisk until stiff peaks form, about 5 minutes. Remove 1/3 of whipped cream from the bowl and place in a Ziploc baggie fitted with a star tip. Gently fold in lemon zest and berries into whipped cream in the bowl.
Trim edges of cake for a clean finish.
Spread cream and berry mix on to cake, leaving a boarder around the edges.
Gently roll cake in order for a spiral to form. Trim the ends of the cake.
With the Ziploc bag and star tip, pipe cream on top of the cake. Garnish with fresh berries and serve.