Melt 50g chocolate. Use a pastry brush to brush a thin layer all over the inside of each cone, then leave to set for 20 mins. Heat the cream and 100g fudge in a small pan for 3-5 mins until melted.
Cut 4 strips of greaseproof paper, each about 7cm wide, then cut them in half. Wrap a strip around the top of each cone, making sure the paper rises at least 2.5cm above the rim. Secure the paper with sticky tape. Place the cones in ice lolly moulds or something similar to help them stand upright.
Drizzle a little fudge sauce into each cone, then use a teaspoon to gently push a little ice cream down into each cone. Drizzle with more fudge sauce, then fill the cone, alternating the layers. Keep adding ice cream until it rises about 2cm above the top of the cone, then smooth the top. Chop the remaining fudge into small pieces and sprinkle over the top. Finely chop some more chocolate and scatter this over, too. Return to the freezer for 2-4 hrs until set.
Try different flavoursFor a strawberry version, whizz together 250g trimmed strawberries with 3 tbsp strawberry jam and use instead of the fudge sauce, swirling a little over the top. Or try double chocolate: stir 50g chopped milk chocolate through the softened ice cream. Make a chocolate sauce by finely chopping 100g dark chocolate and stirring together with 100ml boiling double cream. Assemble the ice cream as before and top with more chopped milk or dark chocolate.