Cream the softened butter and sugar in a large bowl until smooth and fluffy. Add the egg and vanilla extract, mixing until fully combined.
½ cup softened butter, ½ cup sugar, 1 egg, 1 teaspoon vanilla extract
In the same bowl, add the flour and salt. Stir gently, just until the dry ingredients are incorporated. Be careful not to overmix, as this keeps the dough tender.
¼ teaspoon salt, 2 cups all-purpose flour
Fold in the chopped chocolate and walnuts, making sure they are evenly distributed throughout the dough. Shape the dough into a rectangle, wrap it tightly in plastic wrap, and refrigerate for at least 3 hours or until firm.
½ cup chopped chocolate, ½ cup chopped walnuts
Preheat your oven to 350°F (180°C). Roll out the chilled dough on a lightly floured surface to about ¼ inch thick. Use a Christmas tree-shaped cookie cutter to cut out shapes. Place the cookies on a parchment-lined baking sheet, leaving a little space between them.
If you’re planning to hang the cookies as ornaments, use a straw or skewer to make a small hole at the top of each cookie. Chill the tray in the fridge or freezer for 5 minutes to help the cookies maintain their shape during baking.
Bake the cookies for 12 minutes, or until the edges are lightly golden. Remove from the oven and, while they’re still warm, gently re-punch the holes if needed.
Let the cookies cool completely on a wire rack before decorating. Dust with powdered sugar for a snowy effect, or thread a string through the holes to hang them as ornaments. Hang them or place them in gifts bags and enjoy!