I am in the fortunate position that I have access to a fusing kiln and can melt myself such beautiful glass leaves. No worries, thanks to the company Colour de Verre from the USA, it is now quite easy to melt such leaves and a variety of other shapes.
Colour de Verre offers the appropriate molds for this purpose. They just need to be filled with glass crumbs and then, of course, heated in the fusing oven.
This can really anyone who has a fusing furnace.
So ask your glass dealer. He can do it himself or can recommend someone - sure.