Place the 1 cup cocoa powder in a medium bowl and pour the boiling water over it. Stir with a fork until smooth and set aside to cool.
In a medium bowl, combine flour, baking soda, baking powder, and salt. Whisk to mix well.
In the large mixing bowl of an electric mixer, beat butter and sugar on high speed until smooth.
Add vanilla and eggs, one at a time, beating well after each addition and scraping down the sides of the bowl if necessary.
Add flour mixture in 4 batches, beating just until combined.
Add cocoa mixture in 3 additions, stopping to scrape down the sides of the bowl. Once batter is smooth, turn mixer off and divide evenly between the 3 prepared pans.
Place in oven and bake for 25 to 30 minutes or until top of cake springs back when lightly touched.
Place cake pans on a wire rack and let cakes cool in pans for 10 minutes. Remove cakes from pans and place back on wire rack to cool completely.
To make filling, place heavy cream, confectioners' sugar and vanilla in a medium bowl and beat with an electric mixer until thick. Refrigerate until needed.
To make frosting, place butter in bowl of electric mixer and beat until smooth. Add 1 cup of confectioners' sugar and beat until combined. Add half of the cream with the mixer on low and then remaining ingredients, including what is left of cream. Turn mixer to high and beat until smooth.
Spread whipped cream between the cake layers and frosting on sides and top of cake. Store leftovers in refrigerator.
This recipe originally appeared on spicysouthernkitchen.com