In the small bowl or cup, add powdered gelatin and cold water. Mix with a spoon or spatula and set aside.
Place the chocolate in the tall cup.
In the saucepan, over medium heat, bring the heavy cream and lemon zest to a simmer, but do not let it boil.
Pour warm cream over the chocolate and let it sit for a few minutes. Emulsify with an immersion blender.
Add lemon juice and bloomed gelatin. Emulsify again.
Add cold heavy cream and emulsify again.
Transfer ganache into a flat container and cover with plastic wrap "to contact". Refrigerate the ganache for 12-24 hours.
How to Make Lemon Filling
In the saucepan, add lemon juice and sugar. Over medium heat, warm up the mixture, and make sure the sugar has melted.
In the small bowl, mix the egg yolk and cornstarch.
Pour the warm lemon mixture into the egg yolk, and mix with a spatula or whisk.
Pour the mixture back to sauce pan and return to the heat.
Bring the mixture to a boil, mixing with a spatula or whisk. Remove from the heat.
Add butter and mix until all combined.
Transfer the lemon filling into a pastry bag and refrigerate until use.
How to Assemble
Using a hand mixer, whip the ganache and transfer it into a pastry bag. Do not over-whip ganache!
Place the lemon silicone mold on the cutting board or tray.
Pipe ganache into about half of each cavity of the mold. Using a spatula, move ganache to the sides of the mold.
Pipe lemon filling right into the center of the ganache.
Pipe ganache on the lemon filling. After that, using a spatula, level the ganache in each cavity.
Cover with plastic wrap and place in the freezer for at least 12 hours.
How to Make Chocolate Coating
In the saucepan, melt the cocoa butter over medium heat.
Semi-melt the chocolate in the microwave.
Add food coloring to the chocolate, then pour in the melted cocoa butter.
Emulsify with an immersion blender. Make sure the chocolate is melted and there are no chunks left. The working temperature for the coating is 30oC -32oC.
For the final steps, you need to remove each lemon from the silicone mold and dip it into the chocolate coating.
After that, transfer the dessert to the box or tray. Let the dessert defrost in the refrigerator for a few hours before you can enjoy it.
Notes
Measure all ingredients correctly using a digital kitchen scale.