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 (I use a stand mixer with the whisk attachment). Stir until combined.
In a medium bowl, whisk together the oil, buttermilk, eggs and vanilla. Once combined, add in the coffee slowly so you don't cook the eggs.
Pour the wet ingredients into the dry ingredients and stir slowly until combined. 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. (A few moist crumbs sticking to the toothpick is fine, but you don't want it gooey).
Cool for a few minutes. Run a butter knife around the outside of each pan, and turn the cakes out onto a cooling rack.
Glossy Chocolate Frosting
In a saucepan, melt the butter over low heat.
Add the chocolate chips and stir until melted.
Add the sugar, cocoa and salt and whisk together. (It will be a little bit grainy at this point, which is fine).
Whisk in the cream and sour cream. Continue to cook on low heat until hot and smooth, but do not let it boil.
Remove from heat and stir in the vanilla.
Let the frosting cool in the fridge (it'll thicken) until it's at the right consistency.*
Stir the frosting until smooth and frost the cake.
Notes
*If the frosting thickens more than you'd like in the fridge, set it out at room temperature for a bit until it softens.