Preheat a oven to 230°F. Sift powdered sugar and cocoa powder together and mix well with almond flour.

Add a little lemon juice to egg white. Beat until it becomes watery and smooth.

Whip it with a hand mixer on high speed. When it gets white and fluffy, add granulated sugar in 4 parts. Whip it until it forms stiff peaks.

Mix the bottom with a whisk. Whip it with the hand mixer while slowly drawing 10 circles on low speed.

Sift dry ingredients in it in 3 parts with a strainer. Mix it each time while cutting the batter and turning the bowl.

Mix more even after the powderiness disappears. Make heavy batter smooth and soft. Mix it until it fold down like a strip and flows slowly. Put the batter in a pastry bag.

Squeeze the batter on a baking tray. Leave a space between each batter. Hit the bottom of baking tray and flatten each batter.

Crush bubbles with a toothpick. Put it in that oven (process 8) and dry its surface. (Leave the oven off.) Prevent the remaining batter from drying.

Dry till you can touch it without batter sticking. Preheat the oven to 356°F and bake at 302°F for 15 minutes. Bake it until the upper part doesn't move.

Make ganache. Put chopped chocolate in a bowl. Pour hot heavy cream into the bowl, and wait 30 seconds as it is. Mix slowly and melt the chocolate.

Squeeze the ganache on a macaron shell. Top it with another macaron shell to make a sandwich.

Cover with plastic wrap and let it sit for 6 hours at room temperature and for 12-18 hours in a fridge. (Freshly baked macaron is soft and moist but when cooled it gets dry and hard. Please let it sit for a whole day to soften.)