1-Getting started with this Lemon Blackberry Cake begins with simple prep work to ensure even results. First, grease and dust three 8-inch round baking pans and line them with parchment paper for easy removal. Beat the wet ingredients granulated sugar, vegetable oil, large eggs at room temperature, and lemon or vanilla extract until fully mixed, then stir in the lemon zest and juice from two lemons along with full-fat sour cream at room temperature.

2-Next, sift and add the dry ingredients all-purpose flour, baking powder, and salt to the wet mixture. Alternate this with buttermilk or milk at room temperature and fresh lemon juice, mixing on low speed until everything combines smoothly. Fold in the fresh blackberries coated with a small amount of all-purpose flour to keep them from sinking, then divide the batter evenly into the pans.

3-Bake the cakes at 350°F for 28-32 minutes, checking for doneness with a skewer. While the cakes cool, prepare the frosting by chilling your mixing bowl and whisk attachment first. Beat the cold mascarpone cheese on medium-low speed, slowly adding part of the cold heavy whipping cream until it thins out, then add the rest and beat until soft peaks form.

4-Incorporate the powdered sugar and lemon extract, beating until stiff peaks appear for a creamy finish. To assemble, level the cakes if necessary, add a dollop of frosting on a cake board, and layer with frosting and lemon curd. Finish by applying a crumb coat, frosting the top and sides, and garnishing with extra fresh blackberries before chilling.