• Prepare two round 9-inch cake pans by lining them with parchment paper, with a bit of olive oil, and a sprinkle of flour. Set aside. Preheat oven to 350℉.
• In a large mixing bowl, whisk together the sugar and extra-virgin olive oil. Add the vanilla extract, lemon juice, lemon zest, and salt.
• In a separate bowl, sift the cake flour and baking powder together. Alternate adding in the cake flour, ice water, and buttermilk, by adding half of each at a time, mixing throughout. Then add the second half of the cake flour, ice water, and buttermilk. Whisk in the egg whites.
• Finally, fold in the blueberries. To prevent the blueberries from sinking to the bottom of the cake, you can coat them in 2 tablespoons of flour before adding them to the batter.
• Pour the batter evenly between the two cake pans. Bake in the oven for about 35 minutes, or until the cake is done. You'll know the cake is done by putting a toothpick in the center and no wet batter sticks to the toothpick. A few moist crumbs are just fine. Allow the cakes to cool in the pans for about 10 minutes before transferring on to the wire racks to cool completely.

Make the frosting

• In a large mixing bowl, use an electric mixer on medium speed to cream the butter and cream cheese for about two minutes. Once smooth, gradually add in the powdered sugar one cup at a time, making sure to scrape the edges of the bowl as you mix.
• Fold in the blueberry jam, lemon zest, and lemon juice until just combined. Frost the top of the bottom layer cake, then add the second layer before frosting the rest of the cake. Decorate the cake with lemon slices and blueberries. Serve immediately or refrigerate until you're ready to serve the cake!