Preheat oven to 350F.

In KitchenAid mixer or with electric hand-mixer beat your butter until well-creamed.

Add sugar to the mixing bowl and beat with the butter until well combined (about 30 seconds).

Stir in vanilla extract and salt, stirring until well-combined, and scrape down the sides of the bowl using a rubber spatula to ensure ingredients are well-incorporated.

Add egg yolk and beat until combined.

With mixer on medium-low speed, gradually add flour until well-incorporated (you will definitely need to scrape down the sides and the bottom of the bowl several times for this, as the mixture is fairly dry and crumbs tend to settle at the bottom of the bowl).

Transfer dough to clean surface and use your hands to form it into a cohesive ball.

Flatten into a disk (about 1" thick), cover with clear wrap, and chill for 15 minutes.

Once dough has chilled, transfer it to a clean, lightly floured surface and use a lightly floured rolling pin to roll out to about 1/4" thickness.

Lightly flour your cookie cutters and cut out your shapes, transferring them to ungreased cookie sheet.

Once you have cut out all of the shapes that you can, be sure to re-combine the scraps and roll out and cut out again to get the maximum number of cookies from your dough.

Bake on 350F for 10-12 minutes (longer if you are using larger cookie cutters) and allow cookies to cool completely before dipping in chocolate.

Prep chocolate by placing melting wafers (or chocolate chips and shortening) in microwave-safe bowl and microwaving at 15 second increments and stirring in between.

Dip cookies in chocolate as desired (I preferred to hold the bottom of the cookie and press the face into the chocolate, it may be easier to spread the chocolate directly on to the cookies if you are using chocolate chips/shortening instead of melting wafers) and then immediately sprinkle with nonpareils or dip chocolate-side down into shallow dish of nonpareils (the bottom of the dish should be completely covered with the nonpareils if dipping).

Allow chocolate to harden before serving.