Preheat oven to 350F (175C) and thoroughly grease and flour three 8” cake pans or spray with baking spray. To ensure cakes don’t stick, I recommend lining the bottoms of your cake pans with rounds of parchment paper.

In a large bowl (or in the bowl of a stand mixer fitted with a paddle attachment), combine flour, sugars, baking soda, baking powder, and salt and stir.

With an electric mixer (or your stand mixer) running on low speed, add butter, one tablespoon at a time, not adding the next tablespoon until the previous one is fully incorporated into the dry ingredients. Once all butter has been added the mixture should appear slightly sandy in texture.

In a separate bowl or large measuring cup, whisk together buttermilk, eggs, and vanilla extract until combined.

Turn mixer speed to low and slowly pour buttermilk mixture into batter until completely combined. Be sure to pause and scrape the sides and bottom of the bowl as needed. Once finished, batter should be smooth and silky.

Evenly divide batter into prepared cake pans and transfer to 350F (175C) preheated oven (if all of your cake pans do not fit at once it is OK to leave a cake pan on the counter while the other two bake). If your oven bakes unevenly, be sure to rotate cake pans midway through baking. Bake for 30-32 minutes or until a toothpick inserted in the center of the cake comes out clean or with a few moist crumbs (cakes may still be very pale when baked through, this is OK, and yes they are supposed to be thin layers).

Allow cakes to cool in pan for 10-15 minutes then run a knife around the edge of the cake to loosen it from the pan and carefully invert onto a cooling rack to cool completely. Cakes must be completely cooled before assembling!

Combine sugar and cornstarch in a small saucepan and whisk until combined.

Add berries, water, and lemon juice and stir together until ingredients are all combined.

Transfer saucepan to stovetop and turn heat to medium (do not increase heat above medium, heat slowly so the sugar has time to dissolve and the mixture thickens properly).

Stir constantly until berries have released their juices. At this point, take a potato masher or fork and smash/break up the berries.

Continue to stir constantly as the mixture cooks and thickens to a loose jam-like consistency. This may take several minutes. Keep in mind that the mixture will continue to thicken as it cools, so you don’t want it to be too thick when you remove it from the stove or it could become like a paste once cooled.

Transfer berry filling to a heatproof container and allow to cool completely before spreading over cake.

Combine heavy cream, 1 ½ cups powdered sugar (190g), and vanilla extract and use an electric mixer to beat until you have just achieved stiff peaks (meaning the peak that forms when you pull the beater out of the cream holds its shape and doesn’t dissolve back into itself. Normally I would say the peak should stand tall and not fold over, but if it folds over a little in this instance that is fine).

In a separate bowl, combine cream cheese, mascarpone cheese, and remaining ½ cup (63g) powdered sugar. Briefly beat together these ingredients on low-speed just until smooth (mascarpone can become grainy if it is over-mixed).

Add mascarpone mixture to whipped cream mixture and beat on low-speed. Gradually increase speed to high and beat until the mixture is thick and fluffy.

Place one cooled cake layer on a cake plate/serving dish. Use a large round tip (I use a ½” tip/Ateco 826, but you can just use a large ziploc bag with a corner snipped) to pipe a dam along the top edge of the cake, forming a ring.

Fill this ring with ½ of your cooled jam filling, spreading the filling evenly.

Top first layer with a second layer of cake and repeat steps above by piping a dam and filling with remaining jam.

Top with remaining layer of cake. Cover entire cake evenly with mascarpone frosting. You will have a bit extra left to pipe decorative rosettes or other decorations on top, I like to use my Ateco 848 to do additional decorations and then top the cake with additional fresh fruit.

Store cake covered in the refrigerator. Enjoy!