• Prep: Preheat oven to 175°C (350°F) with top and bottom heating mode. Grease a 10- or 12-cup bundt pan thoroughly with shortening, vegetable oil spray or softened butter. Make sure the grease gets into all the grooves. Sprinkle flour liberally over the grease and tap out the excess.

Make the cake

• Dry ingredients: Sift together the plain flour, baking soda, and salt into a mixing bowl. 
• Butter mixture: In a stand mixer fitted with a paddle or using handheld beaters, beat butter and sugar at medium-high speed until light and fluffy, about 4 – 6 minutes, stopping once or twice to scrape down the sides of the bowl with a rubber spatula.
• Add eggs: Add the eggs, one at a time. At first, the mixture will curdle, but continue to beat until the mixture smoothens out before adding the next egg.
• Add dry mixture and buttermilk: Reduce the mixer setting to low speed. Add the flour mixture in 3 lots alternating with the buttermilk, beginning and ending with the flour mixture. Mix in each lot until just combined. Be careful not to overmix, just enough to get the batter smooth and creamy.
• Bloom the cocoa: In a small bowl, stir cocoa and instant coffee granules (optional) in boiling water until dissolved and smooth. Let the cocoa mixture sit for 1 - 2 minutes.
• Add cocoa and vanilla extract: At low speed, beat the cocoa mixture and vanilla extract into the butter mixture until well combined and the batter is at the same consistency throughout. The batter will be quite thin but not runny.
• Fill the bunt pan: Pour the batter into the greased and floured bundt pan. Level and smoothen the surface with a rubber spatula.
• Bake: Bake in the centre of the oven for 50 – 55 minutes, or until the cake tests done. Insert a metal skewer into the centre of the cake. If it comes out clean or with a few crumbs sticking to it, the cake is done. If you see some wet or raw batter, add a few more minutes to the baking time and test again.
• Cool: Remove the pan from the oven and let the cake cool in the pan for 15 minutes. Invert the cake onto a wire rack to finish cooling.
• Serve: When completely cooled, make the chocolate glaze and drizzle over the cake as desired. Top with chocolate curls or shavings.

Make the chocolate glaze

• Place the chocolate chips in a heatproof bowl in the microwave oven. Set the cook time to 2 minutes.
• Start heating on high power setting in short bursts of 15 to 20 seconds, stirring the chips each time you stop. At first they will remain solid, keep stirring to distribute the heat evenly. As soon as most of the chips have completely melted save for a few solid ones, remove from the microwave.

  Note: You may not need the full 2 minutes.
• Add the butter - the heat from the chocolate will melt it - and keep stirring until you get a smooth glaze. Drizzle over the cooled cake as desired.

  Note: If the glaze becomes too thick to pour, reheat in a microwave oven at medium power setting in short bursts of 15 seconds until it is at the desired pouring consistency.