MAKE THE CAKE:
Preheat oven to 350 degrees F. Line the bottoms of 2 8" cake pans with parchment paper and spray pans lightly with baking spray. Set aside.
To the bowl of a stand mixer, add flour, sugar, cocoa powder, baking soda, baking powder and salt. Whisk to combine and remove any lumps.
In a separate mixing bowl, add buttermilk, vegetable oil, eggs and vanilla, and whisk to combine.
Turn stand mixer on LOW speed and slowly pour in wet ingredients, until just combined, scraping sides of the mixing bowl if necessary.
Keep mixer on LOW speed and carefully pour in brewed coffee. Mix until just combined, scraping the sides of bowl again if needed.
Pour batter into prepared pans and bake for 30-35 minutes, until a toothpick inserted into the center comes out clean.
Remove cakes from oven and let cool in the pans for 30 minutes, then turn out gently onto cooling racks to continue cooling. Cool completely.
MAKE THE SYRUP:
Heat a small saucepan over MED heat, and add water and sugar. Stir until dissolved. Let simmer about 3 minutes or so, until thickened slightly. Stir in coffee extract and set aside to cool slightly.
MAKE THE FROSTING:
Add butter to bowl of a stand mixer and cream on MED-HIGH speed until butter is light and fluffy. Butter will be almost white in color.
In a mixing bowl, whisk together powdered sugar, cocoa powder and salt, until no lumps remain.
Add 1/2 of the sugar mixture to butter and beat until combined. Add half the cream and beat.
Repeat with remaining sugar mixture and cream.
Increase mixing speed to MED-HIGH and beat for 3-5 minutes until fluffy.
Add bottom layer of cake to cake stand, drizzle with half of the coffee syrup.
Let stand a minute, then spread a layer of buttercream frosting over the top.
Top with second cake layer. Drizzle with remaining coffee syrup and let stand a minute.
Frost top and sides of the cake.
Decorate with chocolate covered espresso beans if desired.
Refrigerate cake until ready to serve. Remove from refrigerator 30 minutes before eating.