Homemade Chocolate Cake (Reader Favorite!)

INGREDIENTS
Chocolate Cake:
2 cups all-purpose flour
2 cups granulated sugar
3/4 cup Dutch-processed cocoa powder sifted
2 tsp baking soda
1 tsp baking powder
1 tsp salt
1/2 cup vegetable oil
1 cup buttermilk room temperature
1 cup hot water or hot coffee
2 large eggs room temperature
2 tsp vanilla
Chocolate Swiss Meringue Buttercream:
6 large egg whites
2 cups granulated sugar
2 cups unsalted butter room temperature
10 oz good quality dark chocolate chopped, melted, cooled

Assembly:
chocolate curls or sprinkles

INSTRUCTIONS
Chocolate Cake:
Preheat oven to 350F, grease two 8-inch cake pans and dust with cocoa powder. Line bottoms with parchment paper.
Place all dry ingredients into the bowl of an electric mixer fitted with a paddle attachment. Stir to combine.
In a medium bowl whisk all wet ingredients (pour hot water/coffee in slowly as not to cook the eggs).
Add wet ingredients to dry and mix on medium for 2-3 mins. Batter will be very thin.
Divide batter evenly in your prepared pans. I used a kitchen scale to ensure the batter is evenly distributed.
Bake for 40-45 mins or until a cake tester comes out mostly clean.
Cool 10 minutes in the pans then turn out onto a cooling rack to cool completely.
Chocolate Swiss Meringue Buttercream:
Place egg whites and sugar into the bowl of a stand mixer, whisk until combined.*
Place bowl over a double boiler on the stove and whisk constantly until the mixture is hot and no longer grainy to the touch (approx. 3mins). Or registers 160F on a candy thermometer.
Place bowl on your stand mixer and whisk on med-high until the meringue is stiff and cooled (the bowl is no longer warm to the touch (approx. 5-10mins)).
Switch to paddle attachment. Slowly add cubed butter and mix until smooth.**
Add cooled melted chocolate and whip until smooth.
Assembly:
Place a layer of cake on a cake stand or serving plate. Top with approx. 1 cup of buttercream and spread evenly. Place the second layer on top and do a thin crumb coat on the cake. Chill for 20mins.
Place 1 cup of frosting on top and spread evenly. Smooth the sides and flatten the top, then use a large offset spatula to do a swirl pattern on top.
Using a piping bag fitted with a 1M tip, pipe rows of frosting around the cake, starting at the bottom. Apply even pressure as you rotate your turntable. Continue working your way up the cake to the top, making sure the seams all align at the back.
Decorate the top with chocolate curls, pearls, and flakes if desired.