For the cupcake:
1. Preheat the oven to 325° and line muffin pans with papers.
2. Combine the flour, baking soda and salt in a bowl.
3. Cream together the butter or shortening with the sugar until fluffy.
4. Add the eggs one at a time, scraping down the bowl between each addition.
5. Add half of the flour mixture, mix. Add the buttermilk, mix, Add the remaining flour mixture.
6. Fold in the ground acorn flour and mix until incorporated.
7. Bake 8" round for 25-35 minutes, bake cupcakes 12-18 minutes until cake is springy. Cool.
For the frosting:
1. Mix butter and cream cheese until smooth. Add confectioners sugar and mix until stiff, scraping bowl.
2. Add the grape jam. You want a pretty purple frosting. If the frosting is too soft, add more confectioners sugar to help it stiffen. Chill the frosting before frosting the cupcakes, and chill the cupcakes once frosted.