Indulge in Decadent Double Chocolate Bliss!

Preheat the oven to 325 degrees F (165 degrees C).

Make the cake: Sift cake flour, 3/4 cup sugar, cocoa powder, baking powder, salt, and baking soda together into a large bowl. Make a well in the center.

Whisk egg yolks, water, oil, and vanilla together in a large bowl; pour into the well in the flour mixture. Whisk until smooth, scraping down the sides of the bowl if necessary.

Beat egg whites and cream of tartar in a bowl with an electric mixer fitted with a whisk attachment until soft peaks form. Gradually mix in remaining 3/4 cup sugar until well combined. Gently fold in egg white mixture in three portions until just combined.

Pour batter into an ungreased 10-inch, two-part tube pan and smooth the top.

Bake in the preheated oven until a skewer inserted in the center comes out clean, 55 to 60 minutes.

Meanwhile, place a metal bowl and wire whisk into the freezer for at least 15 minutes.

Remove the cake from the oven. Invert the pan onto an upside-down mug to cool completely, about 1 hour. Run a knife around the edges of the cooled cake to loosen it from the pan, then carefully transfer to a cutting board. Use a sharp knife to cut the cake in half horizontally.

Make the frosting: Combine sugar, cocoa powder, and vanilla in the chilled metal bowl and whisk to combine. Stir in 2 tablespoons cream. Add remaining cream and beat with the chilled whisk until peaks form.

Make the glaze: Bring a saucepan of water to a boil. Combine chocolate, butter, and corn syrup in a metal bowl and place over the saucepan; reduce the heat so the water maintains a simmer. Stir until chocolate is melted, about 3 minutes. Remove from the heat and let cool slightly.

Place the bottom half of the cake onto a cake plate and top evenly with about 1 cup frosting; reserve the rest for decorating. Carefully place top layer over filling. Pour glaze over cake and use a spatula to coat the sides with glaze. Fill remaining frosting into a piping bag and decorate cake to your liking.