cups all-purpose flour
teaspoon fine salt
cup Dutch-process cocoa powder
cup boiling water
sticks unsalted butter, at room temperature, plus more for coating the pan
cups granulated sugar
large eggs, at room temperature
1. Heat the oven to 350°F and arrange a rack in the middle. Coat a bundt pan with butter; set aside. 2. Place the flour and salt in a medium bowl and whisk to combine and aerate; set aside. Place the cocoa in a medium heatproof bowl. While whisking constantly, slowly pour in the boiling water and whisk until smooth and combined; set aside. 3. Place the measured butter and sugar in the bowl of a stand mixer fitted with a paddle attachment and beat on medium speed until lightened in color and fluffy, about 5 minutes. Stop the mixer and scrape down the sides of the bowl and the paddle. 4. Add the vanilla and reserved cocoa mixture and beat on medium speed until combined, about 1 minute. Add the eggs 1 at a time, beating well after each addition. Stop the mixer and scrape down the sides of the bowl and the paddle. 5. Turn the mixer to low speed, slowly add the reserved flour mixture, and mix until the flour is just incorporated. Stop the mixer, remove the bowl, and stir in any remaining flour streaks by hand, making sure to scrape the bottom of the bowl. 6. Pour the batter into the prepared pan and spread it into an even layer. Bake until a toothpick inserted into the center comes out clean, about 50 to 60 minutes. Meanwhile, set a wire rack over a baking sheet and set it aside. 7. Remove the cake from the oven and let it cool in the pan on the wire rack for 15 minutes. Remove the cake from the pan and let it cool completely on the wire rack.