Servings 2 Sheet Cakes
Preheat oven to 350°F.
Grease a rimmed 13×18-inch baking sheet and line with parchment paper.
With an electric mixer, beat sugar on high until fine. Empty into a small bowl.
In a separate bowl, stir flour, baking powder and salt until mixed
In a stand mixer, whisk together the eggs and the egg whites on medium speed. Slowly add the fine sugar, followed by the vanilla. Gradually increase the speed to high and whip until pale and thick.
Sift flour mixture over the eggs and gently mix until combined.
Transfer the batter to the prepared baking sheet and smooth out the top with a spatula.
Bake for 10-12 minutes until edges are golden, rotating the pan halfway through baking. The cake should spring back when gently pressed with your finger.
Zest lemon into a small bowl
Heat a medium heavy-bottomed saucepan over medium-low heat, add the lemon zest, SUNNYD Lemonade, egg yolks, and butter and stir to combine. Stir constantly until the butter melts and the mixture thickens, about 12-15 minutes. The lemon curd will continue to thicken as it cools.
Remove from heat and pour lemon curd into a sealable/airtight jar or glass bowl. Press the jar lid directly against the curd so it is airtight. Cool to room temperature and place in the refrigerator. (The curd will thicken when cooled).
When the cake is done, turn it onto greased parchment paper. Tightly roll the cake with the new parchment paper. Let slightly cool, seam side down for 15-20 minutes. Unroll the cake and fill the middle with lemon curd, leaving a ½-inch rim unfilled.
Roll the cake without the parchment and let cool completely. Cut off unfilled ends and transfer to serving platter. Sprinkle with confectioners sugar.