Add the butter, sugar and vanilla into a large bowl and beat using an electric beater on high speed for 1 to 2 minutes or smooth and creamy.
Add the flour, chopped walnuts and salt. Mix until incorporated. Shape the dough into a smooth, flat disc.
Roll between two sheets of parchment until it is less than ¼ inch (.5 cm) thick. Then place the dough on a baking sheet (along with the parchment paper). Chill in the refrigerator until slightly firm, about an hour.
Shape and Bake
Using a 3-inch round cookie cutter, cut out the cookies.
Place one round cut‑out cookie dough circle on a work surface. Using the same round cutter, cut two opposite sides of the circle to form a tree trunk shape.
Take one of the cut edges and gently press it onto one end of the “trunk” piece so they stick together. With a butter knife, make about ¼‑inch slits along the bottom edge of the tree top to create a fringe effect for branches.
Repeat the process to shape the remaining cookies and place them in a parchment-lined baking sheet. Chill for atleast 2 hours (or up to a day)
Preheat oven to 350 degrees F (180 degrees C). Bake for approximately 15 to 19 minutes or until they are a deep golden brown color. This ensures a crisp and crumbly cookie. Cool
Decorate
Melt chocolate chips in a microwave until melted and smooth, about 30 to 60 seconds. Using a small spoon, spread some melted chocolate on the tree tops.
Using a toothpick, make a fringe pattern on the base of the tree top.
Press one candy eyeball on the chocolate. Let stand until the chocolate sets.
Video
Notes
To mince walnuts, add them to a food processor and process until they are finely minced.I recommend chilling both the rolled dough and shaped tree biscuits for several hours, which gives ample time for the dough to firm up before baking.