• Preheat the oven to 350 °F. Line the bottom of two 8"x3" round cake pans with parchment paper, or butter and flour the bottom of the pans (don't butter/flour the sides).
• Combine 2 ounces Dutch process cocoa powder and 4 ounces boiling water in a small heat-proof bowl. Whisk to combine then set aside to cool while preparing the other ingredients.
• Sift 9 ounces cake flour with 1½ teaspoons baking powder and ½ teaspoon table salt, set aside.
• Combine 8 ounces vegetable oil, 4 large eggs, 8 ounces whole milk, 1 tablespoon vanilla extract and 16 ounces granulated sugar in a mixer bowl. Mix on medium speed to combine the ingredients, continue mixing for 2-3 minutes to emulsify the ingredients.
• With the mixer running on low, add the flour and then add the cocoa mixture. Mix until completely incorporated.
• Divide the batter evenly between the two pans. Bake until the top springs back when lightly pressed or a toothpick inserted in the middle of the cake comes out clean, about 30 minutes.
• Cool in the pan for 20 minutes before turning out onto a cooling rack. Cool completely.

Make the Ganache

• Chop 16 oz semi-sweet chocolate into small pieces, none larger than 1/2" or chop roughly and finish chopping in a food processor. Place the the chocolate in a large, heatproof bowl.
• Pour 20 oz heavy cream into a microwave safe bowl or measuring cup and heat until scalding. You want to get the cream as hot as you can without it boiling over.
• Pour the cream all at once over the chocolate. Do not stir for 2-3 minutes to allow the chocolate to begin melting. Gently stir, trying not to incorporate any air, until all the chocolate bits are melted.
• Cover the bowl and set the ganache aside at room temperature to cool completely.

Assembly

• If needed, trim the tops of the cake to make them level. Split each of the cakes horizontally so you have 4 layers. Arrange the layers so that the flat sides of each cake are at the bottom and top of the stack (see process photos).
• Your ganache should be set and at room temperature. If your ganache has gotten cold microwave it briefly to soften it a bit. The ganache will whip up better if it it's softer rather than very firm. Whip the ganache on medium speed until it lightens in color and texture.
• Use about half of the whipped ganache to fill and stack the layers. Use the remaining ganache to ice the cake. Transfer the cake to a serving platter.