Heat oven to 350 degrees, and line a baking sheet with parchment paper. In the bowl of an electric mixer fitter with the paddle attachment, cream butter and sugar. Add vanilla; mix, and then add salt and flour. Mix until thoroughly combined.Advertisement
Roll dough into fifty 3/4-inch balls. On a lightly floured surface, roll each ball into a 6-inch rod. Knot the dough as shown at let. Place on prepared baking sheet. Repeat, spacing cookies an inch apart, until cookie sheet is full.
Bake until cookies are just starting to turn golden, 9 to 10 minutes. Remove from oven, and let cool on a wire rack before removing from paper. Repeat with remaining dough.
Set a heat-proof bowl, or the top of a double boiler, over a pan of simmering water. Add the white chocolate and melt, stirring constantly. Transfer melted white chocolate to a small dish for easier dipping. Dip the ends of the knots in the white chocolate, coating about 1/4 inch, and place on a wire rack to set just a bit, about 10 minutes. Dip each end in sanding sugar to coat thoroughly, and let harden completely, about 25 minutes. Cookies will keep at room temperature for 2 to 3 days in an airtight container.