In a bowl, add cocoa butter & milk powder. Set aside until ready to use.
In a saucepan, add 1st quantity of cream, sugar, and lime zest. Bring to a simmer. Take off heat and cover, and allow to infuse for 5 minutes.
Add back onto the heat and bring to a soft boil.
Pour over cocoa butter & milk powder in 2-3 stages.
Once the 1st cream is incorporated, add gelatin to the mixture. Blend until thoroughly combined.
Add 2nd cream to the mixture and blend until well combined. Strain the mixture and transfer it to an air-tight container covering the top of the ganache with plastic film wrap to prevent a skin from forming.
Set in refrigerator for 24hrs for best results.
When ready to use the ganache, add the desired quantity to a cold mixing bowl. Whisk until medium/hard peaks.
Use immediately after whipping.