Preheat the oven to 350 degrees. Spray 3 6-inch cake pans with non-stick spray, line the bottoms with parchment paper rounds and set aside.
In a medium bowl, whisk together the all purpose flour, cocoa powder, baking powder, baking soda and salt. Then set aside the dry ingredients.
2 cups (250 g) all-purpose flour, spooned and leveld, ¾ cup (60 g) Dutch process cocoa powder, 1 ½ teaspoon baking powder, ¼ teaspoon baking soda, ½ teaspoon salt
In a large mixing bowl, cream together the butter and granulated sugar with an electric hand mixer on high speed until fluffy, about 3-4 minutes. (If using a stand mixer, use the paddle attachment.)
2 cups (400 g) granulated white sugar, ¾ cup (168 g) unsalted butter, softened
Then add in the eggs and vanilla and mix on medium then medium-high speed until smooth, pale in color and slightly fluffy, about 2-3 minutes. Scrape the sides of the bowl with a rubber spatula as needed.
3 eggs, at room temperature, 1 teaspoon vanilla
Add the dry ingredients and the buttermilk to the butter mixture a little at a time, until all has been added, mixing on low then medium speed for each addition. Mix just until the batter is combined and smooth, scraping the sides of the bowl as necessary
1 ¼ cups (300 ml) buttermilk, at room temperature
Add in the hot coffee and mix on low speed just until dispersed through the batter.
½ cup (120 ml) hot coffee
Evenly distribute the cake batter between the prepared cake pans. Bake the cakes for 39-44 minutes, or until a toothpick comes out clean from the centers. Let the cakes cool in the pans for 5 minutes, then transfer to a wire rack to completely cool.