Mashed Potato Chocolate Cake: Thanksgiving Leftovers

Still have leftovers from Thanksgiving? I posted Thanksgiving Leftovers Recipes for Turkey Mole and Cranberry Sauce Truffles. Here's another favorite!  Today is National Cake Day, so use what you have! I have mashed potatoes, so here's a recipe for Mashed Potato Chocolate Cake. There are lots of Mashed Potato Chocolate Cake recipes, but this one is very easy. This recipe won't work if you seasoned your potatoes with herbs or garlic. Mashed potatoes with butter or cream or cream cheese will work perfectly. In case you want to make this as it's own dish (not using leftovers), try the recipe I posted for White Chocolate Mashed Potatoes.  I've never met a potato I didn't like!

MASHED POTATO CHOCOLATE CAKE

Ingredients
4 oz. dark chocolate (65-75% cacao)
1 cup sweet butter
1 3/4 cups sugar
4 eggs
1 cup mashed potatoes
1 cup buttermilk
1 tsp. Madagascar or Mexican vanilla extract
2 cups cake flour
1 tsp. baking powder
1/2 tsp. baking soda
1/2 tsp. salt
2 ounces dark chocolate chopped into chip size

Directions
Melt chocolate with vanilla; cool slightly.
Sift together flour, baking powder, soda, and salt.
In another bowl, cream butter and sugar and beat in eggs one by one.
Add chocolate and mashed potatoes.
Beat in the dry ingredients alternately with the buttermilk.
Fold in dark chocolate 'chips'.
Pour into a greased 13x9 x 2  inch pan (or Bundt Pan) and bake in a preheated 350 degree oven for approximately 40 minutes. Cool before frosting.

OPTIONAL FROSTING
3 oz. chocolate-65-85% cacao
1-1/2 tsp. Madascar vanilla extract
1 lb. confectioners' sugar
Dash of salt
1/2 cup softened  sweet butter
Hot milk
Chopped walnuts

Melt chocolate and vanilla. Let cool slightly. Cream sugar, salt and butter. Add just enough hot milk to spread. Beat in melted chocolate. Spread on cake and sprinkle with chopped nuts.