In a liquid measuring cup, mix milk and vinegar and set aside. Best to leave all room temperature ingredients out overnight, so that they have time to reach temperature. The milk is ready when it’s curdled. If you’re ready to begin baking, now is the time to turn on the oven to 350 degrees, and start the kettle for boiling water.

Using a large bowl, sift cake flour and cocoa powder, then add into the sifted ingredients the sugar, baking powder, baking soda, and salt. Use a whisk to combine thoroughly, scraping the bottom of the bowl to make sure you don’t miss any.

In a medium bowl mix curdled milk, eggs, and canola oil.

Pour wet ingredients into dry and use a wooden spoon to mix until everything is incorporated. Consistency should be like thick brownie batter.

Using a whisk, slowly mix boiling water into batter. Whisk carefully until the water is incorporated, then whisk vigorously for about 15 seconds until the batter is nice and smooth. The texture should be very runny.

Use extra room temperature butter to carefully coat 3 cake tins, then line with parchment cake pan liners. Evenly pour the batter into each pan, roughly 700g each.

Bake all three on the same oven tray, staggered as best as you can, until cooked through. This will take roughly 30-40 minutes depending on the size of the pans. Test the cakes by inserting a toothpick into the center of each cake. The toothpick should come out clean.

Set on a cooling rack for about 10 minutes, then lift the cakes out of the tins, and continue to cool until they reach room temperature. At least an hour, and more if you have it. After they reach room temperature, you could wrap them tightly in plastic and freeze until you’re ready to frost, or go ahead and begin frosting.

While the cakes cool, begin the buttercream frosting. In a double boiler, melt chocolate and set aside.

Using the same pot with water, heat the sugar and the egg whites, stirring frequently, until they reach 160 degrees. Use a candy thermometer and be patient. This process will take a few minutes, and may require more water into the double boiler pot. I find the slowest increase in temperature is from 150 until it reaches a temperature of 160.

Once the egg whites and sugar come to temperature, transfer to a stand mixer equipped with the whisk attachment. Beat the mixture on high speed until stiff peaks form, about 5-7 minutes. To test, lift the mixer arm out of the bowl, the meringue should be bright white and a long strand of merengue should just about connect the lifted whisk and the bowl.

Add in vanilla bean paste and salt. Mix to combine.

Set the mixer back to high speed and drop the butter in, one cube at a time letting each cube disappear into the mixture before adding the next, until fully incorporated. The texture may look curdled halfway through, keep adding and it will come together. If it hasn’t by the time you’ve finished slowly adding the butter, beat on high for a few more minutes.

Switch to the paddle attachment and pour in the cooled melted chocolate. Mix on medium speed until fully incorporated and smooth in texture.

Begin layering and frosting the cake. Cut the tops off the cake, and depending on the size cake pan you used, slice the cake into two layers. Place a small blob of frosting onto the cake plate, and begin layering. Using about 1 cup of frosting per layer. Use an offset spatula to frost, and if you have time, create a crumb layer – or a lightly frosted cake with visible cake spots peeking through - to catch all the loose crumbs.

Frost the final coat using a large offset spatula, then switch to a small offset spatula to fill in any bare spots and to frost as close to the plate as you can get. Here you could pipe on a design, or get creative with how you want the frosting to look. If you prefer a heavily frosted cake or want to pipe a lot of frosting, double the amount of SMBC you make.

Decorate with frozen berries, florals, or a dusting of cocoa, and enjoy!