Beat butter, sugar and vanilla until light and fluffy. Stir in flour, walnuts and half-and-half; beat until smooth. Shape into 1-inch/25-mm balls and place on ungreased baking sheet. Bake at 400°F/200°C for 12 minutes or until set but not brown. Cool slightly, roll in powdered sugar and set on wire rack to cool. Mix additional powdered sugar, and cinnamon to taste; roll balls again in cinnamon/sugar mixture. Store in well-sealed containers.