Pour the isomalt crystals and water into a sauce pan, give it a little stir and turn the heat on high
Heat until it reaches 320 F degrees (don't go over, it will result in yellowing/haziness and don't go under - a good candy thermometer is key)
While that's heating lay out the silver leafing, in a 3x4 pattern. (I use a silpat mat cause it's holds the silver leafing in place)
ALSO preheat your oven to 320 F (again an oven thermometer comes in handy)
As soon as the candy reaches 320 F turn off the heat and quickly stir in a few drops of candy flavoring if you desire.
Carefully pour the hot isomalt candy over the silver leaf, the higher you pour from the more the candy will stretch out and pop the bubbles, but it will also cool faster.
Immediately rotate the pan from side to side to help it spread across the silver leaf.
If it cools too much and stops spreading before you have reached every side and corner place it in the preheated oven for 2 mins, then do it again, it will warm back up and spread even further.
Then let it cool.
If you want a specific shape, rectangle, circle, etc... in your mirror as soon as you can touch it but it's still warm and soft you can slice and cut into the sugar, carefully, then let it cool completely, you'll be able to break out the shapes you cut fairly easily.