Granne's Chocolate Sheath Cake

Cake:
2 cups self-rising flour
2 cups sugar
1 stick butter
1/2 cup canola oil
1 cup water
4 TBSP cocoa
1/2 cup buttermilk
2 eggs, slightly beaten
1 tsp baking soda
1 tsp cinnamon
1 tsp vanilla

Frosting:
1 stick butter
4 TBSP cocoa
1/2 cup milk
1 box powdered sugar
1 tsp vanilla
1 cup chopped nuts (we like pecans)

Cake:
In medium bowl, stir together flour and sugar.  In a saucepan, bring butter, canola oil, cocoa, and water to a rapid boil.  Boil until all is melted together.  Pour over flour and sugar mixture and mix with spoon (do not beat).  In a separate bowl, whisk together buttermilk, eggs, soda, cinnamon, and vanilla until well-incorporated.  Mix with batter.  Pour into greased 9x13 metal cake pan and bake at 350 for 25 to 30 minutes.

Frosting:
In a saucepan, melt butter, cocoa, and milk. Do not bring to a boil.  Steep until all is well-blended.  Sift powdered sugar and pour into cocoa mixture.  Mix until powdered sugar is dissolved.  Add vanilla and nuts and stir.  Pour over hot cake.  Allow to cool most of the way before serving.