Preheat the oven to 180°C.
Line two large baking sheets with baking paper.
Cream the butter with the sugar until light and fluffy.
Beat in the egg and vanilla extract until the mixture is smooth.
Then stir in the flour, baking soda, salt and 150g Toblerone.
Drop tablespoons of dough onto each sheet (5cm apart).
Press the remaining chopped Toblerone over the surface of the cookies.
Bake for 10-12 minutes, just until dry-looking.Leave to cool and firm up on the baking sheets.