Preheat the oven to 350F. Grease three 6" or 7" cake pans w/ butter & dust w/ flour. Line the bottom w/ parchment paper rounds.

Cake Layers: In a large bowl, whisk together the flour, sugar, cocoa powder, baking soda, baking powder & salt.

In a separate large bowl, whisk together the buttermilk, avocado oil, eggs & vanilla until combined.

Add dry ingredients to the wet; mix to combine. Then, pour in the hot coffee & stir quickly until combined (batter is will be very thin).

Divide the batter evenly among the cake pans (~455g of batter in each). Bake at 350F for 25-27 mins, until a toothpick comes out clean.

Remove & cool completely in the pans.

Frosting: In a saucepan over medium heat, add the butter, chocolate & heavy cream. Sift in the powdered sugar, cocoa powder, salt & espresso powder.

Mix constantly until smooth. Remove from heat & mix in vanilla.

Pour the mixture into a large bowl or baking pan. Cover w/ plastic wrap so it's directly touching the frosting, to prevent a film from forming. Cool at room temp for 30 mins, then chill in the fridge for at least 1-2hrs.

Assemble. Using a serrated knife, thinly slice the tops of each cake layer off to even.

Place 1 cake layer cut side up on a cake stand or platter. Spread ~¼ of the chocolate frosting all over the top. Repeat w/ remaining layers.

After the last cake layer, spread the remaining frosting all over the cake. Decorate & garnish as desired.

Slice & serve.