Preheat your oven to 350°F (175°C). Prepare your cake pans by greasing them and lining the bottoms with parchment paper.
In a large mixing bowl, whisk together the all-purpose flour, unsweetened cocoa powder, granulated sugar, baking soda, baking powder, and salt.
In a separate bowl, combine the room temperature eggs, sour cream, canola or olive oil, and vanilla extract. Whisk together until fully blended.
Pour the wet mixture into the bowl with the dry ingredients. Using a rubber spatula, gently fold them together until just combined.
Gradually stir in the very warm/hot water until the batter is smooth and well combined.
Divide the batter evenly between the prepared cake pans. Bake for 30-35 minutes, or until a toothpick inserted into the center comes out clean.
Once baked, remove the cakes from the oven and allow them to cool in the pans for about 10 minutes. Then, transfer them to a cooling rack to cool completely.
To make the Swiss Meringue Buttercream, heat egg whites and sugar over a double boiler until sugar dissolves. Whip until stiff peaks form, then gradually add softened butter until smooth.
Once the cakes are completely cool, place one layer on a serving plate. Spread Swiss Meringue Buttercream on top, then place the second layer on top. Frost the sides and top of the cake.
Grate semi-sweet or milk chocolate over the top of the cake for decoration. Slice, serve, and enjoy!
