01 - Preheat oven to 350°F. Grease and line two 9-inch round cake pans with parchment paper.
02 - In a large bowl, sift together flour, cocoa powder, sugar, baking powder, baking soda, and salt.
03 - Add eggs, milk, oil, and vanilla extract to the dry mixture. Beat on medium speed for 2 minutes until smooth.
04 - Stir in boiling water carefully; batter will be thin.
05 - Divide batter evenly between prepared pans.
06 - Bake for 30 to 35 minutes until a toothpick inserted in the center comes out clean.
07 - Allow cakes to cool in pans for 10 minutes before transferring to wire racks to cool completely.
08 - Place chopped chocolate in heatproof bowl. Heat cream until simmering and pour over chocolate. Let sit 2 to 3 minutes, then add butter and stir until smooth and glossy. Cool until thick but pourable.
09 - Place one cake layer on serving plate. Spread ganache evenly over top. Add second layer and cover top and sides with remaining ganache.
10 - Let set at room temperature or refrigerate to firm ganache before slicing and serving.