• Preheat the oven to 350 degrees Fahrenheit and grease three 9-inch cake pans with cooking spray or butter. Line the pans with parchment paper circles, then grease the parchment paper.

Make the Cake:

• In the bowl of a stand mixer fitted with the paddle attachment, or a handheld mixer, beat the butter on high speed for about 1 minute or until creamy.
• Add the granulated sugar and the brown sugar and beat on medium-high speed for about 3 minutes or until creamy.
• Add the eggs and the vanilla and beat on medium speed for about 2 minutes or until combined, scraping down the sides of the bowl as needed.
• In a large bowl, whisk together the flour, baking powder, and salt. Slowly add the dry ingredients to the wet ingredients. Beat on low speed for about 10 seconds, then add the milk, lemon zest, and lemon juice and beat until just combined. Don’t over beat.
• Toss the blueberries with 1 tablespoon of flour and gently fold into the batter. The batter will be thick.
• Divide the batter evenly into the prepared cake pans. Bake for about 21-25 minutes or until a toothpick inserted in the center comes out clean.
• Remove from the oven and allow to cool completely in the pan before assembling and frosting.

Make the Whipped Mascarpone Frosting:

• Add the heavy whipping cream, confectioners’ sugar and vanilla extract to a mixer bowl and whip on high speed until soft peaks form.
• Add the mascarpone and whip until stiff peaks form. This happens quickly. You can store the frosting in the fridge.

Assemble the Cake:

• To assemble the cake, use a large serrated knife to remove the domes from the top of the cakes, if needed.
• Place the first layer of cake on a serving plate or a cardboard cake round.
• Place half of the whipped mascarpone frosting in a piping bag fitted with a large open round tip. Pipe a layer of frosting on top of the cake layer and spread evenly. Then spread half of the lemon curd over mascarpone filling.
• Add the second layer of cake and repeat the above steps using all of the remaining lemon curd. Next, add the final layer of cake on top.
• Use your piping bag to fill in any gaps between your layers, then frost the outside of the cake.
• If you have enough frosting, you can pipe a few swirls on the top of the cake. Garnish with blueberries and lemon slices (optional).