This decadent Blackberry Jam Cake has a rich, buttery cake that’s bound to become one of your favorite cakes to whip up. It's frosted with a blackberry frosting.
Preheat the oven to 350ºF. Grease with shortening, then dust with flour two 8-inch round cake pans. (You can use 9-inch cake pans but the cakes will be thinner and will bake faster.)
In a large bowl (with a stand mixer or electric mixer) cream together the butter and sugar for 2-3 minutes on medium speed.
Add the eggs and mix until combined, scraping the sides of the bowl as needed.
In a small bowl, whisk together the flour, allspice, cinnamon, nutmeg, salt, baking powder and soda. Whisk well.
Add the flour mixture to the wet ingredients and beat until well mixed.
Add the jam and sour milk. Mix on low speed until combined.
Divide the batter evenly between the two pans.
Bake for 30-35 minutes or until the center of the cake springs back when you touch it. (Or a toothpick inserted into the cake should come out clean.)
Allow the cakes to cool for 5 minutes, then turn out onto a wire rack to cool completely.
Make the frosting:
In a large bowl, whisk together the melted butter, lukewarm heavy cream and vanilla extract.
Add the powdered sugar, 1 cup at a time, mixing well while you are adding the sugar.
Mix until the frosting is smooth, thick and creamy.
Assemble the cake:
Place one cake layer on a cake plate. Spread about ½ cup of frosting on top of the cake.
Place the second cake layer on top. Frost the outside top and sides of the cake with the remaining frosting.
Decorate the top of the cake with blackberry jam and fresh blackberries if you’d like.
Store in an airtight container at room temperature for up to 3 days.