Mix 1 tbsp hot water with 1 tsp coffee powder to create coffee water. Let it cool.

Sift the dry ingredients (cake flour, cocoa powder, baking powder) together several times to combine well.

In a bowl, beat the egg and mix in the sugar until well combined.

Add the sifted dry ingredients to the egg mixture and mix well.

Add the cooled coffee water to the batter and mix thoroughly.

Add 1 tbsp olive oil and mix until the batter is smooth.

Pour the batter into a microwave-safe cup or paper cup.

Microwave uncovered for 1 minute 30 seconds. For smaller cups, microwave for 40 seconds, test with a skewer, and add more time if needed.