Preheat the oven to 350f and grease two large baking sheets
Cream butter and sugar in a large bowl until light and fluffy.
Add in the corn syrup and egg and mix until combined.
Stir in the chocolate and vanilla.
Mix together the flour, baking powder and salt then add this into the butter mixture and beat well.
Stir in the walnuts.
Roll heaped teaspoons of the cookie dough between your hands to form a ball then place onto a greased or lined baking sheet leaving two inches between each cookie
Place in the oven to bake for 10-15 minutes until the edges are firm.
Leave to cool for a few minutes on the baking sheets before transferring to a wire rack to cool completely.