Step by step

1. Heat oven to 175ºC. Arrange two racks in center of oven. Butter three 20-by-5-cm round cake pans; line bottoms with parchment. Dust bottoms and sides of pans with cocoa powder; tap out any excess.

2. Attach Sifter Attachment to KA Stand Mixer (with Beater Attachment), and press "Tare" to zero scale.

3. Add dutch-processed cocoa powder into the ingredient hopper and weigh. Turn Stand Mixer to speed 4 and sift cocoa into a medium bowl, and whisk in boiling water. Set aside to cool.

4. Cream 340 g of butter on speed 2 until light and fluffy.

5. Add 450 g of sugar to ingredient hopper and weigh. Turn Stand Mixer to “stir” and gradually sift in sugar until light and fluffy. Beat in vanilla. Drizzle in eggs, a little at a time, beating between each addition until the batter is no longer slick.

6. Whisk milk into reserved cocoa mixture.

7. Add and weigh flour, baking soda, and 1/2 tsp of salt to ingredient hopper, pressing "Tare" between the addition of each ingredient. Give hopper ingredients a stir to combine. With mixer on “stir”, sift dry ingredients in. Add cocoa mixture to the batter a little of each at a time.

8. Divide batter evenly among the three prepared pans. Bake until a cake tester inserted into center of each layer comes out clean, 35 to 45 minutes, rotating the pans for even baking. Transfer layers to wire racks; let cool, 15 minutes. Turn out cakes, and return to racks, tops up, until completely cool.

9. Frosting - In bowl of stand mixer with beater attachment, beat 110 g of butter until smooth on speed 4 for 1 minute. Add 290 g of powdered sugar and 75 g of cocoa powder. Turn to speed 2 and slowly add in milk, vanilla and 1/4 tsp of salt and mix for 4 minutes until smooth.

10. Remove parchment from bottoms of cakes. Reserve the prettiest layer for the top. Place one cake layer on a serving platter; spread 1/4 of the chocolate frosting over the top. Add the second cake layer, and spread with another 1/4 of frosting. Top with third cake layer. Cover outside of cake with the remaining frosting. Serve.