Blackberry Cake

Preheat oven to 350°F. Coat a 9-inch springform pan with baking spray. Combine cake mix, eggs, 1/2 cup melted butter, buttermilk and lemon juice in a large bowl. Beat with an electric mixer on medium-high speed until completely combined and smooth, about 2 minutes. Gently fold in blackberries. Pour the batter into the prepared pan and smooth the top.

Bake until a wooden pick inserted in the center comes out clean, 45 to 50 minutes. Let cool in the pan on a wire rack for 20 minutes. Gently run an offset spatula around the sides of the cake; remove the sides from the pan. Gently remove the cake from the bottom of the pan. Let the cake cool completely on the rack, about 1 hour.

Beat cream cheese, jam and the remaining 1/4 cup softened butter in a large bowl with an electric mixer on medium speed until completely smooth, about 2 minutes. Reduce speed to low and gradually add confectioners' sugar. Increase speed to medium-high and beat until light and fluffy, about 1 minute.

Place the cooled cake on a serving platter and spread frosting over the top and sides of the cake. Garnish with blackberries, if desired.