Prepare ingredients

• Shred the zucchini using a box grater, medium-sized cut (see photo below). Squeeze the zucchini in your hands over a sink to squeeze out some of the juice. Don’t squeeze too much out as we want some of the liquid to moisten for the cake. 
• In a microwave or on the stove, melt the butter and let it cool down slightly. 
• Chop the chocolate unless using small chocolate chips.

Mix the batter

• In a large bowl, whisk together the eggs, yogurt, melted butter and brown sugar until smooth and thick. 
• In a separate smaller bowl, combine flour, cocoa powder, baking powder, baking soda and a good pinch of salt. 
• Add the dry ingredient mix to the wet ingredients, top with shredded zucchini and chopped chocolate. Mix through until well incorporated. The mixture will seem very thick when you start mixing but will quickly moisten and soften to a very thick batter.

Prepare the cake pan

• Grease the sides of a 7-7.5″ springform cake pan with butter. Cut out a circle-shaped piece of parchment paper, place it on the bottom and brush with butter as well. You can use your fingers to grease both.  

Add cake mixture to the pan

• Transfer the cake batter to the prepared cake pan. Use a spoon or a spatula to spread the batter evenly into the sides and smooth the top. The mixture will sink in and spread further while baking. Cover the cake pan with a sheet of foil to prevent the condensation droplets inside the pressure cooker from falling on top of the cake. 

Set to cook the cake in the Instant Pot

• Add a cup of water to the bottom of the Instant Pot. Place the trivet with the handles folded on the bottom. Gently lower the cake pan inside the pot. You can make a long foil sling under the cake pan, which will make it easier to lift it out once cooked.
• Secure and lock the lid. Set to Pressure Cook (Manual on older models) on HIGH pressure for 45 minutes. The pressure will take about 5-7 minutes to build up and the timer will kick-off. Once down, allow the pressure to release naturally, which will take about 12-14 minutes. 
• Open the lid. Use a towel, tongs or the pre-made foil sling to lift the cake pan out of the pot. Transfer it to a plate and lift the foil cover. Allow to cool in the pan, then release the springform sides. Gently flip the cake over onto a plate or a cutting board and slide off the bottom part of the pan. Place the cake, top side up, on a serving plate or cake stand. 

Make the chocolate glaze

• To make the glaze/ganache, you can use the Instant Pot, stove or microwave (see notes below). To use the Instant Pot, press the Saute function and add a cup of boiling/hot water to the pot. Place the trivet on top and make sure the water doesn’t go above the level of the trivet. Place a heat-proof bowl inside the pot on the trivet. Add the chocolate chips and butter and allow to melt over steam/heat coming from the bottom. IMPORTANT: make sure to stir frequently and as soon as MOST of the chocolate and butter are melted, remove from heat and stir through for the remaining bits to melt through. If you leave it on the heat for too long, the glaze will start to cook and thicken and turn grainy. 
• Glaze the cake while the chocolate mix is still runny, spread it evenly over the cake with a spatula.