Preheat your oven to 180°C (350°F). Grease and line two 8-inch round cake pans with parchment paper.
In a heatproof bowl, melt the chopped dark chocolate over a saucepan of simmering water, stirring occasionally until smooth. Set aside to cool slightly.
In a large mixing bowl, cream together the softened butter and granulated sugar until light and fluffy. Add the eggs, one at a time, beating well after each addition.
In a separate bowl, whisk together the all-purpose flour, baking powder, and cocoa powder. Gradually add the dry ingredients to the butter mixture, alternating with the melted chocolate, beginning and ending with the dry ingredients.
Divide the batter equally between the prepared cake pans. Smooth the tops with a spatula and bake in the preheated oven for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
Remove the cakes from the oven and allow them to cool in the pans for 10 minutes. Transfer the cakes to a wire rack to cool completely.
While the cakes are cooling, prepare the whipped cream. In a chilled mixing bowl, beat the heavy whipping cream, powdered sugar, and vanilla extract until stiff peaks form.
Once the cakes have cooled, carefully slice each cake horizontally into two even layers. You should have four cake layers in total.
Place one cake layer on a serving plate and spread a generous amount of whipped cream on top. Arrange a layer of drained cherries over the cream. Repeat this process with the remaining cake layers, ending with a layer of whipped cream and cherries on top.
Use the remaining whipped cream to frost the sides of the cake. Decorate the top with chocolate shavings, and if desired, add a few whole cherries for an extra touch of elegance.
Refrigerate the cake for at least 4 hours, or overnight, to allow the flavors to meld together and the cake to set.
Once chilled, slice and serve your homemade Black Forest Gateau to delight your taste buds and impress your guests!