Step 1. For the cake: Preheat the oven to 350˚. Coat three 8-inch spherical cake pans with cooking spray and dirt with flour. Line the underside of every pan with a spherical of parchment paper.
Whisk the granulated sugar, flour, baking powder, baking soda and salt in a big bowl. Put aside. Soften the butter in a small saucepan over medium-low warmth. In the meantime, mix the moment espresso and boiling water in a medium bowl and stir to dissolve.
As soon as the butter has melted, add the espresso combination to the saucepan. Let it come to a boil for about 10 seconds, then take away from the warmth and put aside.
Step 2. In a separate medium bowl, whisk the buttermilk, eggs and vanilla till nicely mixed. Pour the butter-coffee combination into the flour combination and stir gently.
Add the buttermilk-egg combination and stir gently till nicely mixed. Divide the batter among the many ready pans.
Bake till a toothpick inserted into the facilities comes out virtually clear, 23 to 25 minutes. Enable the desserts to chill for quarter-hour within the pans on a rack, then take away the desserts from the pans, take away the parchment and let cool on the racks.
Step 3. For the frosting: Beat the butter in a big bowl with a mixer on excessive pace till gentle and fluffy, about 1 minute.
Add the powdered sugar and salt and beat on low pace to include. Stir the moment espresso into the heavy cream in a small bowl, then pour it into the mixer.
Beat on low pace till mixed, then beat on excessive pace till gentle and fluffy, about 2 minutes, including a bit of extra cream if wanted