Preheat oven to 350.
Mix flour and sugar in bowl. Set aside.
Mix salt, baking soda, vanilla and buttermilk, eggs in bowl. Set aside.
Boil together in sauce pan, butter, oil and cocoa and water.
Add chocolate mixture to flour and sugar. Stir.
Add in remaining wet ingredients. Mix.
Bake jars at 350 degrees for 15-20 minutes until a toothpick comes out clean. If using mason jars, fills 1/3 full, no more than 1/2. This cake does not rise very high, but with a rich ganache filling you don't need a lot of this cake. You will probably have some cake batter left over, which can be baked in a smaller pan and used later. If baking in pan, I suggest a square or rectangular sheet cake so the cake can be cut into small squares for serving.
GANACHE FROSTING (Instructions below)
Chop chocolate into small pieces.
Bring heavy cream to boil.
Pour over chocolate. Let it sit unstirred for five minutes.
Stir, staring in center and remain in center. I like to use a honey dipper for this but you can use a mini-whisk. Just stay in center, keep stirring, until all chocolate is incorporated into cream.
Stir in vanilla, whiskey and cool.
SPECIAL NOTE: Don't fill the mason jars all the way to the top if you plan on freezing. Leave at least 1 inch of space between cake and lid.