Preheat your oven to 350 degrees Fahrenheit.
In a medium sized bowl combine the cocoa powder, 1/2 cup (100 grams) of sugar and the hot water. Stir well to combine and set aside.
½ cup (60 grams) cocoa, ¼ cup (60 mL) hot water
In another small bowl combine the flour, baking powder, vanilla powder and salt. Whisk until well combined.
2 cups (300 grams) all purpose flour, 2 tsp baking powder, ½ tsp vanilla powder, ½ tsp salt
In the large bowl of a stand mixer, beat together the remaining sugar (1 cup or 200 grams) and the eggs until well combined. Slowly pour in the olive oil and continue to mix.
3 eggs, large, ¾ cup (175 mL) olive oil
With the speed set to low, carefully add 1/2 of the flour mixture to the oil/egg/sugar combination in the stand mixer. Beat until well combined. Pour in 1/2 cup (125 ml) of orange juice. Continue beating and then add the remaining flour, followed by the remaining 1/4 (50 mL) cup of orange juice. Scrape down the sides of the bowl using a rubber spatula and then beat well for a minute until all of the ingredients are well combined.
Remove approximately 2 cups of this cake batter and add it to the bowl which contains the cocoa powder, sugar and water. Using a whisk mix it well by hand so that all of the plain batter is combined with the cocoa batter.
Into the remaining batter (the one not mixed in with the chocolate) mix in the orange zest and the orange blossom water, if using it.
2 tbsp orange zest, 1 tsp orange blossom water
Grease a loaf pan. Pour enough of the orange batter into the pan to cover the bottom surface. Then, using a large spoon, drop spoonfuls of the cocoa batter on top of the plain batter. Leave approximately 1/3 of the cocoa batter in the bowl.
Pour the remaining orange batter into the pan, and then pour in the rest of the cocoa batter.
Bake in the middle rack of your oven for 50 – 60 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cake to cool in the pan for about 5 minutes before transferring it to a cooling rack to cool completely.
When the cake is completely cooled you can dust it with icing sugar if desired.
Enjoy!