Preheat your oven to 350°F. Prepare three 6-inch cake pans. Divide the batter evenly between the pans and bake until a knife inserted in the centre of each cake comes out clean, 20–24 minutes.

Sift the flour, sugar, cocoa powder, baking soda, baking powder, and salt into a large bowl and set aside.

Place the milk, coffee or water, oil, egg, yolk, and vanilla in another large bowl and whisk together until smooth.

Pour the wet mixture over the dry ingredients and whisk until smooth. Finish off by folding the batter with a silicone spatula, making sure to scrape the very bottom of the bowl and checking for any dry ingredients that may have escaped the whisk.

Place the pans on a wire rack. Allow the cakes or cupcakes to cool completely on a cooling rack before decorating.

Place the butter in the bowl of the stand mixer and sift in the icing sugar. Fit the mixer with the paddle attachment and start mixing on low speed. Once the icing sugar has been incorporated increase the speed to medium. Scrape down the sides of the bowl as needed. Beat until light and fluffy, 3–5 minutes. Add the tahini and vanilla and mix until smooth and fully combined.

Place the chocolate in a heatproof bowl. (If you’re using a chocolate bar be sure to roughly chop it into small pieces.) Bring the cream to a simmer over medium heat and pour it over the chocolate. (Do not allow the cream to boil). Allow the mixture to stand without stirring for 5 minutes and then whisk until smooth.

Allow the ganache to cool at room temperature until slightly thickened and glossy, about 10 minutes, and then pour it over your cake. Slightly cooling the ganache when it is being used as a glaze will prevent it from being too thin and rolling right off of the cake. Ganache that’s poured too warm won’t have a smooth, shiny, luxurious finish. If this happens, don’t worry. Just cool your bowl of ganache a bit more, and then pour a second layer onto the cake.

Trim the tops of the cake layers if necessary.

Place one cake layer on your cake turntable, top it with some tahini icing, and use an offset spatula to spread it right to the edges of the cake. Fit a piping bag with a round tip and fill it with tahini icing. Pipe a border of icing around the outer edge of the cake and fill the centre with a few tablespoons of ganache glaze, followed by half of the halva. Add the second layer of cake followed by more tahini icing but no ganache or halva this time.

Add the third layer of cake and pipe the remaining tahini icing all over the top and sides of the cake. Use an offset spatula to spread the icing around and then use a cake scraper to clean up the sides of the cake. Pour the remaining ganache glaze on top of the cake and use the offset spatula to move it around, allow-ing it to drip over the sides. Garnish the cake with pistachios and the remaining halva.