Heat the oven to 350 degrees Fahrenheit and position the racks toward the center. Lightly grease and flour (or use Baker's Joy spray) 2 9-inch round cake pans. Set aside.
Sift the flour, baking powder, baking soda and salt together. Add the instant espresso and stir to combine. Set aside.
Whisk the eggs for 20 seconds, then add the sugar and whisk an additional 30 seconds until thick and frothy.
Add the oil and vanilla, and beat until combined. Alternate the flour mixture and buttermilk and beat until combined.
Divide the batter between the 2 cake pans, trying to keep it as even as possible.
Bake for 30-40 minutes. When finished baking, cool in the pan for 30+ minutes.
Remove the cake layers from the pans and finish cooling them on the wire racks.
As the cake layers cool, make the beer caramel buttercream filling and espresso buttercream.
For the filling, beat the butter until light and fluffy.
Add 1/2 cup of sugar, beating until combined. Add the caramel and remaining sugar gradually and whip until light and fluffy.
For the espresso frosting, whip the butter until light and fluffy.
In a small bowl, mix the vanilla and 2 tbsp of espresso powder, stirring until fully combined. Set aside
Add 1 cup of confectioners sugar to the butter and mix to combine.
Add the vanilla/espresso mixture and mix to combine.
Add 3 cups of sugar, 1 cup at a time, mixing in between each addition.
Add the 2 tbsp of espresso powder, as well as the remaining sugar. Add cream as needed to smooth out the consistency of the frosting.
Whip until light and fluffy.
To assemble, place the bottom layer on a cake round. Trim the top off to make an even layer.
Using an offset spatula, add the beer caramel buttercream to the top of the first layer, covering evenly.
Trim the top off the second layer, turn it cut-side down and place on top of the filling. Place in the freezer to chill for about 20 minutes.
Apply a crumb coating of frosting (this doesn't have to be perfect, since the entire cake, after frosted, will be coated with chocolate). Chill for 20-30 minutes in the freezer.
After chilling, frost the cake with the remaining frosting, leaving approximately 1/2 cup to pipe on for the cherry garnishes.
Press the chopped chocolate into the frosting, covering the cake. Pipe 8 rosettes onto the cake evenly and top with the cherries.
Serve at room temperature, and if you want to make it a true Portal Cake, place a single small candle in the middle.