Soak the sheet gelatin in a bowl of cold water for 10 – 15 minutes to bloom.
Bring a small pot of water to a boil.
Turn off the burner and place the white chocolate in a metal or glass bowl. Place bowl on top of the open pot (this is called a bain-marie or double boiler).
Important: Make sure the bowl is dry and no water is present, or it will seize the chocolate and not allow it to melt.
Stir mixture until the chocolate is completely melted. Set aside.
In another small saucepan, bring milk to a simmer and remove from heat.
Remove the sheet gelatin from water. Squeeze out any excess water and add the sheets to the scalded milk. Whisk for one minute.
Combine the melted chocolate and milk mixture, whisk together, and chill in the refrigerator for 20 minutes or until cool, but not set.
Add the heavy cream into the chilled mousse base and whisk until combined.
Pour the mousse base into 1 Qt. whipping siphon and charge with two N20 cartridges.
Place the siphon in refrigerator and allow mousse to chill for at least one hour.
Best served on a chilled serving plate.
Dispense a small amount of white chocolate mousse on the plate.
Immediately after, using a caviar spoon gather a spoonful of raspberry spheres.
Drain any excess liquid and gently place over the mousse, serve immediately