Preheat the oven at 170ºC/340ºF conventional oven and line 2x 20 cm/8 inch baking pan with parchment paper.
Start by boiling some water and weighing it out so it can cool down a bit while preparing the other ingredients.
120 g boiling water
In a bowl, add granulated sugar and orange zest. Rub it together between your fingers to extract the orange flavor from the zest. Add the dark brown sugar and sift in the remaining dry ingredients. Give it a stir to make sure everything has been combined.
200 g granulated sugar, 3 tablespoon orange zest, 100 g dark brown sugar, 240 g all-purpose flour, 4 teaspoon cornstarch, 50 g unsweetened cocoa powder, 1 teaspoon baking powder, 1 teaspoon baking soda, 1 teaspoon salt
In another mixing bowl add all of the wet ingredients, including hot water, and with a hand whisk, whisk them together until combined. Be sure to not mix the ingredients too vigorously so the eggs don’t get over mixed.
120 g orange juice, 180 g sour cream or greek yogurt, 110 g vegetable oil, 2 large eggs, 2 teaspoon vanilla extract
Slowly pour the wet ingredients into the dry while gently stirring it all together. Make sure there are no lumps left in the batter.
Pour the cake batter into the prepared baking tins and bake them for 28-30 minutes or until a cake tester comes out clean.
Let the cakes cool on a cooling rack. After 5 minutes, gently remove the cakes from the cake tins and let the cakes cool down completely.