Line the bottom of three 9 inch cake pans with a circle of parchment paper and grease the sides. Set aside. Preheat your oven to 350 degrees Fahrenheit.
In a medium bowl, whisk the boiling water into the cocoa powder until smooth. Set aside. Allow the mixture to cool while you are preparing the other ingredients. It can be warm when you add it in Step 5, but it can't be hot or steaming.
1 cup unsweetened cocoa powder, 2 cups boiling water
In a large bowl whisk together the flour, baking soda, baking powder, and salt.
2 3/4 cups all purpose flour, 1/2 teaspoon baking powder, 1/2 teaspoon table salt, 2 teaspoons baking soda
In a large bowl with a hand mixer or in the bowl of a stand mixer fit with paddle attachment, beat together the butter and sugar. Beat until light and fluffy, about 3 to 6 minutes.
1 cup unsalted butter, 2 1/2 cups granulated sugar
Add in the eggs, one at a time. Then add in the vanilla extract. Scrape down the sides between each addition, making sure to scrape the bottom of the bowl as well. Finally, beat in the cocoa mixture.
4 large eggs, 1 1/2 teaspoons vanilla extract
Add all of the flour mixture. Start the mixer on low and as soon as you can, turn the mixture up to full speed just until the flour mixture incorporates. This process should take less than a minute.
Divide the batter between the three prepared baking pans. Bake for 25 to 30 minutes. You know your cake is done when a toothpick inserted into the middle of the cake comes out with just a few crumbs.
Allow the cakes to cool in their pans for 10 minutes before inverting them onto a wire rack to allow them to cool completely.