Cream butter in a large mixing bowl; gradually add sugar, beating well. Add eggs, one at a time, beating mixture well after each addition.
Dissolve soda in buttermilk, stirring well. Add flour to creamed mixture alternately with buttermilk mixture, beginning and ending with flour. Mix well after each addition. Stir in crumbled mincemeat.
Spoon batter into 2 greased and floured 8-inch round cake pans. Bake at 300° for 45 to 50 minutes or until a wooden pick inserted in center comes out clean. Cool in pans 10 minutes; remove layers from pans, and let cool completely.
Spread Caramel Cream Frosting between layers and on top and sides of cake.