In the bowl of an electric mixer fitted with a paddle attachment, mix together the butter, confectioner’s sugar and vanilla until they are just combined and fluffy.
Add the flour, a little at a time until it is all combined.
Remove the dough from the bowl onto a floured surface and shape into 2 flat discs. Wrap in plastic and chill for 30 to 60 minutes. At this point, you could chill the dough overnight or freeze it.
Roll out the dough on a floured surface into ½ inch thickness. Using a rectangle cookie cutter, begin to cut out shapes. Place the cut out shapes onto a parchment-lined cookie sheet.
Transfer baking sheets to refrigerator and chill 30 minutes.
Right before baking, use a toothpick to poke 9 holes in the cookies as seen in the photos.
Bake in a preheated 350 degrees for 8 to 10 minutes or until the edges are beginning to brown slightly.
Remove shortbread from baking sheets, and place on wire racks.
Notes
Allow the cookies to cool completely to room temperature before storing in an airtight container at room temperature for up to one week.
Make sure you layer the cookies between parchment paper so the cookies don't stick to each other.
If it's warm in your house, the cookies should be stored in the refrigerator so the chocolate doesn't melt.