Preheat oven to 350º F/ 180º C. Grease and flour very well a small bundt pan.
In a bowl combine cocoa powder, flour, baking soda and baking powder. Mix to blend and set aside.
In a large mixing bowl whisk together eggs and sugar for about 1 minute, until smooth. Add oil and vanilla extract and whisk again, until combined. Add also the yogurt and whisk to combine.
Gradually add the dry ingredients, folding them gently with a rubber spatula, until absorbed.
Pour the batter into the prepared pan. Bake for about 30 minutes or until a toothpick inserted in the centre comes out clean.
Let the cake cool completely in the pan.
Carefully run a knife around the edges and then invert it on a serving plate. Pour the glaze on top. Sprinkle with orange zest and/ or decorate with candied orange peel.
Melt the chocolate in a double boiler. Add the orange juice and orange extract. Mix well and pour on top of the cake.
To grease the pan: place some oil, shortening or cooking spray and 1 tbsp flour in the pan. Use a kitchen brush to mix them and spread very well the mixture around the pan until every surface is covered.
You can substitute all or half of the all-purpose flour with the same quantity of whole grain spelt flour.
Alternatively instead of coconut sugar you can use brown cane sugar.
Store the cake in airtight container for 2-3 days at room temperature or 4-5 days in the fridge.
This cake is small. For a standard bundt pan you need to double the ingredients.