1 (18.5 ounce) white cake mix
1/3 c. vegetable oil
1/2 c. seedless blackberry jam (plus additional 1/3 cup for filling, if desired)
1 cup buttermilk
1/2 teaspoon cinnamon
1/2 teaspoon allspice
1/4 teaspoon nutmeg
Cream Cheese Icing
1/2 cup (1 stick) butter or margarine
1 (8 ounce) package cream cheese, softened
1 tablespoon milk or half-and-half
1 teaspoon vanilla
1 (1 pound) box powdered sugar
Preheat oven to 350 degrees. In large bowl, combine all ingredients and beat on high speed for 2 minutes, then divide batter between 2 greased and floured round cake pans.
Bake for 20 to 25 minutes, or until cakes test done. If you want to fill the layers with jam, read the instructions for using the jam filling below.In a medium bowl, cream butter and cheese until light and fluffy. Beat in milk and add vanilla; add powdered sugar, two cups at a time, blending well after each addition, until icing is smooth.
Using Jam Filling
A jam filling really enhances the flavor. In order to keep it from seeping out the sides and discoloring the icing, take some icing on the top of a knife and spread a it in a ring 1/2 inch from the edge of the cake layer. Try to make it thick, say 1/4 inch deep. then just spread the jam within this icing ring, place the second cake layer on top and frost the top and sides of the cake.
Source: Quick Fixes with Mixes Cakes, Cookies, Bars and Goodies by Lia Wilson