Sift flour and salt. Set aside.

Beat together butter and sugar in a large bowl with an electric hand mixer until pale and fluffy, about 5 minutes.

Beat in the egg, yolk, and vanilla.

Reduce speed to low, then add flour mixture and mix until combined.

Form dough into three 4-inch logs, about 2-inches in diameter, on a sheet of plastic wrap, and roll dough up in the plastic wrap.

Chill dough on a flat surface until firm, at least 1 hour or overnight.

Preheat oven to 350 F.

Line baking sheet with parchment paper.

Roll cookie logs in sanding sugar or sprinkles, coating evenly, and slice into 1/4-inch rounds.

Place cookies on baking sheet about 1 inch apart.

Bake until golden brown, 15 – 20 minutes.

Remove from oven and let cool completely on wire racks.