Place sugar in a small pot. Stir with a small amount of water, just to make it the consistency of wet sand. Make sure there is no sugar crystals on the side of the pot. Cook without stirring until it reaches a dark caramel color
Remove the vanilla bean from the cream and pour the hot cream onto the caramel little by little (watch out for splatter!).
Bring the caramel mixture to a boil and cook to about 240F degrees (around 5/7 minutes) and pour onto the chopped chocolate, add the butter and vigorously mix until you obtain a shiny texture. Add the walnuts and immediately pour into a silicon pan, let harden for 12 hours in the refrigerator
Remove from pan onto a cutting board. Cut circles with cutter and stick in the lollipop sticks