Preheat oven to 350º F. Grease three 9-inch cake pans (I also like to cut a circle of parchment paper for the bottom of the pan to make sure the cake doesn't stick). Set aside.
In a large bowl whisk together the flour, sugar, cocoa, baking powder, baking soda, and salt.
Add milk, oil, eggs, and vanilla to flour mixture and mix until well combined.
Slowly add boiling water to the cake batter, while stirring. Beat on high speed for about 1 minute. The batter will be very thin.
Pour cake batter evenly between the three cake pans.
Bake for 30-35 minutes or until a toothpick inserted in the center comes out clean or with few moist crumbs.
Remove from the oven and allow to cool for a few minutes before inverting onto a cooling rack.
For the frosting:
Stir together the powdered sugar and cocoa powder. In a separate mixing bowl beat the butter on medium speed until pale, about 2 minutes.
Gradually add the sugar/cocoa mixture alternating with the cream and vanilla, beating after each addition, until you reach your desired frosting consistency.
Beat on high speed for 3 minutes, until fluffy.
Assemble the cake:
Lay one layer of chocolate cake on a cake board or platter. Use a spatula or the back of a spoon to spread a layer of dark chocolate frosting over the top of the cake. Add the second layer or cake and frost the top and sides of the cake.
Freezing Instructions: After allowing the cake to cool completely, wrap each cake round in plastic wrap and store in a freezer safe bag in the freezer for a couple days or up to three months. Remove the cake rounds from the freezer and frost immediately. Store in the refrigerator and remove to the counter about 30 minutes before eating.You can also freeze the assembled, frosted cake. Cover it as well as you can (without smashing the frosting) with plastic wrap and then aluminum foil. Freeze for up to 1 week and allow to thaw on the counter for about a 1.5 hours before serving.Variations to Dark Chocolate Cake:
Gluten-free dark chocolate cake: substitute gluten free flour at a 1:1 ratio.
Dairy-free dark chocolate cake: substitute soy or almond milk for the regular milk in the recipe and for the heavy cream in the frosting. Substitute a dairy free butter in the frosting.
Vegan chocolate cake: make dairy- free substitutes and substitute three flax eggs or 3/4 cup plain yogurt for the eggs.