Preheat the oven to 150°C (300°F/Gas 2).
Place the fondant and glucose in a saucepan and heat to 150°C (300°F). Stir in the chocolate. Working quickly, pour the mixture onto a sheet of baking paper, top with another sheet and, using a rolling pin, roll out to 1 mm (1/32 inch) thick. You may need to place the mixture on a baking tray and warm in the oven to soften, if it gets too hard.
Remove the top sheet of paper and cut into six 10 × 6 cm (4 × 2½ inch) rectangles. Warm in the oven for 2 minutes to soften, then sprinkle evenly with the sesame seeds. Return to the oven for another 2 minutes to soften. Working quickly and with one rectangle at a time, wrap a rectangle around a cone mould. Allow to cool and harden, then remove from the mould. Set aside.
These can be made up to 1 day in advance and stored in an airtight container.