Combine both ingredients in a bowl and melt them over a hot water bath. If using soon, keep the spray liquid by keeping it warm (above 40°C/105°F) over a warm water bath. If not, reserve in an airtight container at room temperature for up to 1 year.
To fill the molds, make sure the chocolate shells are frozen.
Churn the ice cream base to medium smoothness, not all the way; otherwise, it cannot be piped into the mold and will not fill it completely. Pour it from the machine directly into a piping bag.
Pipe the ice cream into the shells and fill them to the top. Even out the top with an offset spatula. Reserve all of the filled shells frozen at -10°C/14°F.
Let the ice cream harden for at least 2 hours. Meanwhile, set up a spray station, a surface that should be covered with plastic to keep the shop clean where you can spray the chocolate velvet spray.
Fill a compressor canister with the caramelized white chocolate spray. Spray the ice cream-filled shells with an even coating of spray. Keep the compressor gun at least 60cm/24in from the shells to obtain a velvety smooth look.
Keep the shells well covered to prevent frost from forming on their surface. Make sure that you do not touch the surface of the shells with either plastic wrap or your hands, however, since it will scuff the velvet. Discard after 3 days.