Step 1

Preheat oven to 350° F (177°C). Grease the bottom and sides of 1 or 2 ( 8-inch) round cake pans with non-stick spray. Place parchment rounds on the bottom. Set aside. If you only have 1 or 2 8-inch pans, take out 4-5 bowls to divide your batter in later.

Step 2

In a large bowl, sift flour, cocoa, salt, baking soda and baking powder. Whisk to combine, set aside.

Step 3

In the bowl of a stand mixer fitted with a paddle attachment, or in a large mixing bowl using a hand mixer, beat the butter and sugar on medium-high speed until pale and fluffy, 4-5 minutes. Scrape down the sides and bottom of the bowl.

Step 4

Lower the speed to medium-low and add eggs one at a time, mixing after each addition until just combined. Scrape down the sides and bottom of the bowl.

Step 5

In a small bowl, combine the vanilla and instant coffee granules. Add the sour cream to the batter along with the vanilla/coffee mixture and beat on medium speed until combined. Batter will be curdled.

Step 6

Alternately add dry ingredients in thirds and buttermilk in 2 additions to the batter, beginning and ending with the dry ingredients. Beat each addition just until combined.

Step 7

Divide batter equally in 6 portions. I added a scoop of batter to 2 cake pans, then a scoop to 4 bowls and repeated until all the batter was done. Cover the other bowls of batter and set aside.

Step 8

Bake two layers at a time for 18-20 minutes or until a toothpick inserted into the center comes out clean and cake springs back when lightly touched.

Step 9

Remove cakes from oven and allow to cool in pans for about 10 minutes, then turn onto cooling racks to cool completely before frosting.

Step 10

Bake another 2 layers and repeat. Once those are cooled, bake the final 2 layers. Wrap all the cooled layers and store them in the refrigerator to chill and set up to make it easier to handle. See post above for tips on how to handle the layers without breaking.

Step 11

Place chopped chocolate in a medium bowl. Set aside.

Step 12

Heat 1/4 cup of heavy cream in a small saucepan, stirring constantly until it just begins to simmer.

Step 13

Remove hot cream from the heat then pour it over the chocolate, and slowly stir until smooth. Cover the bowl and transfer to the refrigerator to cool down, stirring every 5-10 minutes for about 20-30 minutes or until ganache is completely cooled. Alternatively, you can let it cool at room temperature.

Step 14

Once ganache has cooled, whip 1/2 cup of heavy cream with the powdered sugar in a stand mixer fitted with a whisk attachment, or in a medium stainless steel mixing bowl using a hand mixer, on high speed until it reaches stiff peaks, about 2-3 minutes.

Step 15

Remove the ganache from the refrigerator and stir to loosen. Use a rubber spatula to gently fold the whipped cream into the ganache, about 1/3 at a time until fully incorporated and no white streaks remain.

Step 16

Cover the bowl with plastic wrap, placing the wrap directly onto the mousse surface. Refrigerate for 1-2 hours or overnight.

Step 17

Place the chopped chocolate and butter pieces into a large bowl. Set aside.

Step 18

Heat the heavy cream in a medium saucepan until it just begins to simmer.

Step 19

Remove hot cream from heat then pour it over the chocolate and butter. Cover the bowl and allow it to sit for 5 minutes.

Step 20

Remove cover and gently stir mixture until it forms a smooth ganache.

Step 21

Place bowl in the refrigerator and stir every 20 minutes until the ganache is a thick, spreadable consistency. This took me around an hour, but it really depends on the coldness of your refrigerator.

Step 22

Use an offset spatula to place a dollop of ganache onto a cake board or serving platter that’s on a turntable. Place one cake layer on top and spread about 1/2 cup of the ganache on top.

Step 23

Add a second layer on top and spread on half of the mousse.

Step 24

Repeat with all layers, alternating between ganache and mousse. You should have 3 layers of ganache and 2 layers of mousse. Place the final layer upside down.

Step 25

Chill the cake for 30 minutes so the layers can set back up. Stir remaining ganache occasionally to keep it loose.

Step 26

Once chilled, remove the cake from the refrigerator and frost the top and sides with the remaining ganache.

Step 27

Pour mini chocolate chips into a bowl and grab large handfuls to press up the sides of the cake. You may want to have a large pan or container under the cake to catch any spills. Go around the cake once with the chocolate chips, then go back to fill any gaps.

Step 28

Carefully cut your chocolate squares in half and place on top of the cake. Slice and serve!