Preheat oven: Preheat the oven to 356ºF (180ºC). Line a round 8-inch baking pan with parchment paper, and set aside. Note: Alternatively, if you have a non-stick pan, liberally grease it with softened/spreadable butter and dust it with a light layer of cocoa. This will leave your finished cake with smooth sides.
Mix dry ingredients: In a medium-size mixing bowl, add flour, baking powder, both sugars, and salt. Whisk until well combined and set aside.
Sift cocoa powder: In a separate large mixing bowl, sift in the cocoa powder.
Add coffee powder: Whisk through the instant coffee.
Add boiling water: Pour in boiling water and whisk until the cocoa dissolves. Set aside to cool slightly for 10 minutes. If it’s still too warm to the touch, leave it for a further 5 minutes — you don’t want the eggs to curdle when added.
Add wet ingredients: Pour in olive oil, eggs, and vanilla. Whisk for 40 seconds until well combined.
Combine wet and dry: Add half of the flour mixture and whisk until just combined. Add the remaining flour and beat until incorporated, ensuring not to over-mix — just until no streaks of flour remain. Batter will be thin.
Pour into pan: Pour batter into the prepared pan.
Bake: Bake for 28–30 minutes or until a skewer inserted into the middle comes out clean or with only a few moist crumbs.
Cool: Remove from oven and allow to cool in the pan for 10 minutes.