Using a small paring knife, slice dates open lengthwise and remove pits. Replace pit with half a walnut piece (or whole one depending on size of date). Squeeze date back together.
Place sugar in a small bowl. Some dates have a natural stickiness on the outside, but to ensure the sugar sticks, take a pastry brush and slightly dab the outside of the date to moisten it. Roll stuffed date in sugar until coated. Place on a piece of parchment or wax paper. Continue until all the dates have been sugared.
Once the sugar has hardened to dates, place in an airtight container. To give as gifts, place dates in a holiday tin or wrap in clear food gift bags and tie with ribbon.
Notes
Buying pitted dates cut down on prep time.
You won't use the whole cup of sugar, but it makes it easier to quickly roll the dates to cover them.