Preheat oven to 350°F.

Grease two 9" round cake pans and line the bottom with parchment paper.

Add flour, sugar, cocoa powder, salt, baking powder and baking soda to your mixing bowl. Stir until combined.

In a medium bowl, whisk together the oil, buttermilk, eggs and vanilla.

Pour the wet ingredients into the dry ingredients and stir slowly until combined.

Add the coffee slowly. Then mix on high for two minutes, scraping the sides halfway through.

Distribute the batter between the two prepared pans.

Bake for 35-45 minutes, or until a toothpick comes out clean.

Cool for a few minutes, then run a butter knife around the outside of each pan, and turn the cakes out onto a cooling rack.

In a saucepan, melt the butter over low heat.

Add the chocolate chips, heavy cream, powdered sugar, cocoa powder and salt; stir until melted and hot (but not boiling).

Remove from the heat and whisk in the sour cream and vanilla until smooth.

Pour the frosting through a sieve to remove any possible clumps.

Cover the frosting with plastic wrap so a film doesn't form on top.

Let the frosting cool in the fridge until it's at the right consistency.

Stir the frosting until smooth and frost the cake.