In a large bowl combine butter, sugar and vanilla.Add flour and walnuts. Stir until well blended.Cover and leave the mixture in the fridge for 1 hour to cool.Heat oven to 375 F degrees.Remove wrappers from chocolates.When dough is firm enough to handle, take the dough with a measure of about 1 tablespoon and shape it around each chocolate kiss and roll it to make a ball.(Cover each chocolate completely.)Place balls on a baking sheet lined with baking paper.Bake at 375F for 12 minutes or until cookies are set but not browned.Cool slightly and remove from baking sheet.Roll them in powdered sugar while they’re still warm.Before serving, add more powdered sugar, if desired.