This is a lovely decoration that's surprisingly simple to do if you have a template. Filigree is a design piped in a delicate, usually loopy, design, and placed vertically or horizontally on a dessert. It can be made using royal icing or melted chocolate. You can even create multidimensional decorations by piping flat pieces and gluing them together with melted chocolate.
The easiest way to create filigree is to place a picture of the design you'd like to duplicate on a flat surface under a sheet of waxed paper or cooking-grade acetate.
Place the filigree material in a pastry bag fitted with a writing tip and trace the design. Allow the filigree to set in a cool room, or refrigerate for 3 to 5 minutes.
Carefully remove the filigree from the waxed paper or acetate with a metal spatula. Try not to touch the piece too much; this prevents fingerprints and melting.
Place on a cake or store in an airtight container in a cool place. If you need to stack the pieces, place a piece of waxed paper between each layer.