Preheat oven to 325°F. Line a 9-inch x 13-inch baking pan with parchment paper, leaving a 2-inch overhang on two sides.
In a large bowl, cream the butter, sugar and salt with a handheld mixer until light and fluffy. Alternatively, use a stand mixer fitted with a paddle attachment. Add the egg yolk and vanilla and beat until combined. Add flour and slowly mix until just combined. Transfer to prepared pan and use your fingers to press dough into an even layer, about 1/2-inch thick. Bake for 35-40 minutes, or until edges just turn golden.
Remove from the oven and let cool. Pour warmed caramel sauce over the surface and spread into a smooth, even layer. Refrigerate at least 3 hours to fully chill.
Run a knife along the edge of the pan, then use the parchment paper sling to pull bars out of pan. Grease your cookie cutters with cooking spray and cut the bars into shapes. Alternatively, use a sharp knife to cut into small bars. Place bars in the freezer every so often to keep caramel firm enough to cut. Freeze cut out cookies completely.
Line a baking sheet with parchment paper. Melt the chocolate in a double boiler over low heat. Use 2 forks to dip and roll the cookies, one at a time, into the melted chocolate. Tap off excess chocolate and place on prepared baking sheet. Repeat with remaining cookies. Refrigerate about 10 minutes until chocolate is set. Store, covered and refrigerated, for up to 5 days.