Ingredients
2cupsall-purpose flourscoop and level to measure
¼cupcornstarch
¾tspbaking powder
½tspbaking soda
½tspsalt
1½cupgranulated sugar
2tbsplemon zest
¾cupunsalted buttersoftened
4largeeggs
1tspvanilla extract
½cupbuttermilk
½cupsour cream
2tbspfresh lemon juice
3¼cuppowdered sugar
⅓cupfresh lemon juice
fresh strawberriesraspberries or blueberries for topping
lemonssliced, for decoration (optional)
mint leavessliced, for decoration (optional)
Preparation
Preheat oven to 350 degrees F. Butter a rimmed 18×13-inch baking sheet (average size cookie sheet), dust with flour then shake out the excess.
In a mixing bowl, whisk together flour, cornstarch, baking powder, baking soda, and salt for 20 seconds, set aside.
In the bowl of an electric stand mixer fitted with the paddle attachment, mix together sugar and lemon zest for 30 seconds until fragrant and slightly yellow in appearance.
Add butter and whip mixture on medium speed until very pale and fluffy. Mix in eggs one at a time then blend in vanilla extract.
In a bowl or 2-cup liquid measuring cup, whisk together buttermilk, sour cream, and lemon juice. Add 1/3 of the flour mixture to the butter mixture and mix on low speed just until combined then add in 1/2 of the buttermilk mixture and mix just until combined.
Repeat once more with flour and buttermilk then end by mixing in the last 1/3 of the flour mixture just until combined. Scrape down sides and bottom of the bowl with a rubber spatula and fold batter several times to ensure it’s evenly incorporated.
Pour and spread batter evenly onto the prepared baking sheet (it will seem thin but it should bake up nearly to the top). Bake for 22 to 25 minutes until the toothpick inserted into the center comes out clean. Cool completely on a wire rack.
In a mixing bowl, whisk together powdered sugar and lemon juice until smooth (If needed you can add a little more powdered sugar to thicken or more lemon juice to thin).
Pour and spread glaze over cooled cake. Chill for 20 minutes to help set glaze (it won’t set fully but to get cleaner cuts you’ll need it to set slightly). Top with berries, lemon slices and mint just before serving.
