Black Cocoa Chocolate Cake

My Dad's birthday is at the end of November and we like to have a cake at Thanksgiving to celebrate while everyone is all together.
My Dad looooooooooves chocolate and his only request for cake was "something chocolate".
I found this cake recipe while scoping for new chocolate cake recipes and was intrigued by "black cocoa". Thanks to Amazon, I got my black cocoa and went to baking.
I paired it with this buttercream recipe and it was rich, but not too rich and definitely not as rich as it looks, chocolately, and absolutely delicious....even my dog thought so.

yield: one double layer 8" square cake or one double layer 9" round cake or one single layer 13"x9" cake

ingredients
for cake
2 C sugar
1 3/4 C all-purpose flour
3/4 C unsweetened cocoa powder
2 tbs black cocoa
2 tsp baking soda
1 tsp baking powder
1 tsp salt
2 eggs, room temperature
1 C buttermilk
1 C strong black coffee
1/2 C vegetable oil
2 tsp vanilla extract

for chocolate buttercream
1 C salted butter, room temperature
3 1/2 C powdered sugar
1/2 C unsweetened cocoa powder
2 tbs vanilla extract
4 tbs heavy cream

directions

1. for cake: Preheat oven to 350°.
2. Grease and flour two 8" square (or two 9" round or one 13"x9") baking pans.
3. In the bowl of a stand mixer fitted with the paddle attachment, combine sugar, flour, cocoas, baking soda, baking powder, and salt on low speed until thoroughly combined.
4. Add eggs, buttermilk, coffee, oil, and vanilla.
5. Beat on medium speed for two minutes (the batter will be very thin).
6. Pour batter evenly into prepared pans.
7. Bake for 30-35 minutes for round or square pans, 35-40 minutes for rectangular pan; until a toothpick comes out clean.
8. Cool in pan for 10 minutes.
9. Flip cake(s)s out of pan(s) onto a cooling rack; let cool completely.
10. for buttercream: Cream butter for 4 minutes on medium-high speed in bowl of a stand mixer fitted with the paddle attachment.
11. Add powdered sugar and cocoa to the mixing bowl (while turned off in order to avoid a cloud).
12. Beat on lowest speed until combined.
13. Add vanilla, cream and increase speed to medium; beat for 3 minutes.
14. Spread or pipe onto cooled cake(s).
15. Enjoy!