Cream the butter and sugar

• Beat the softened butter and sugar until light and fluffy.
• Mix in the vegetable oil.

Add the eggs and vanilla

• Add the eggs one at a time, beating well after each addition.
• Mix in the vanilla extract.

Combine the dry ingredients

• Whisk together the flour, cocoa powder, baking powder and salt in a bowl.

Combine the wet ingredients

• Mix the buttermilk, sour cream, white vinegar and red food coloring in another bowl.

Make the batter

• Alternate adding the dry ingredients and the buttermilk mixture to the butter mixture, beginning and ending with the dry ingredients.
• Mix just until combined.

Fill the pan

• Pour the batter into a greased and floured Bundt pan.
• Smooth the top.

Bake

• Bake until a toothpick inserted in the center comes out clean.

Cool

• Let the cake cool in the pan, then turn it out onto a cooling rack.

Make the icing

• Whisk the powdered sugar, melted butter, vanilla extract and heavy cream until smooth.

Ice the cake

• Pour the icing over the cooled poundcake.