This chocolate spider web cake features three layers of chocolate cake frosted in a simple chocolate American buttercream and decorated with melted marshmallow spider webs!
Yield: three layer 6-inch cake
Preheat oven to 350°F. Line three 6-inch round cake pans with parchment paper. Lightly grease and set aside.
In a large bowl, whisk together flour, cocoa powder, espresso powder, baking powder, baking soda, and salt. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment, beat together oil, sugar, eggs, and vanilla until well combined.
On low speed, alternate adding dry flour mixture and milk. Add about 1/3 of flour mixture. Mix on low speed until almost incorporated. Follow with half of milk. Mix on low. Repeat adding another 1/3 of flour and remaining half of milk. Scrape down bowl as needed to ensure thorough mixing. Add sour cream and remaining 1/3 flour. Mix on low speed until there are no longer any streaks of dry flour.
Divide batter among prepared cake pans (about 370 g per cake pan). Level batter. Bake for 25-28 minutes until toothpick inserted in center of cake comes out clean. Rotate cakes midway through baking.
Allow cake to cool in pan for 5 minutes before unmolding. Run mini offset spatula around perimeter of cake to loosen from pan, if necessary. Let cakes cool to room temperature on wire rack.
In the bowl of a stand mixer fitted with a paddle attachment (or using an electric hand mixer), cream butter until smooth. Add confectioners' sugar, cocoa powder, salt, and milk. Mix until buttercream is smooth.
Level cooled cakes as needed. Place on cake layer on cake stand or serving plate. Spread about 1/3 cup of chocolate buttercream over cake.
Place second cake layer on top, spread buttercream, and top with third cake layer.
Spread a thin layer of buttercream around the sides of the cake to seal in the crumbs (crumb coat). Place in the fridge and allow to chill for 20 minutes to set buttercream.
Coat cake with another layer of buttercream. Keep in the fridge until ready to decorate with marshmallow webs.
Place marshmallows in a microwave safe bowl. Microwave for 20-30 seconds until marshmallows have puffed up. Stir and until smooth. Allow to melted marshmallows to cool and thicken, about 3 minutes.
Use two forks to pull out about a tablespoon of marshmallow mixture. Stretch and pull into strands and gently drape over top and around the sides of frosted cake. Alternatively, use your fingers to stretch and drape marshmallows over cake.