Preheat oven: Preheat to 375°F (190°C). Line a baking sheet with parchment paper or a silicone mat.

Cream butter and sugar: Beat softened butter, sugar, and salt together for about 3 minutes until light and fluffy. Add egg and vanilla; beat 1 minute until smooth.

Add flour: Sift in cake flour gradually in three parts, mixing gently after each addition until dough is thick and slightly sticky. If too stiff to pipe, add a few drops of milk to soften.

Pipe cookies: Transfer dough to a piping bag fitted with a large closed star tip (such as Ateco 846 or 844). Pipe 2‑inch rosettes, S‑shapes, or other festive forms onto the prepared sheet.

Bake: Bake for 10 minutes or until edges are lightly golden. Cool completely on the baking sheet before decorating.

Prepare ganache: Heat chopped chocolate and heavy cream in a microwave‑safe bowl in 20‑second intervals, stirring between each, until smooth and glossy. Add cream if needed to adjust thickness.

Decorate: Dip cooled cookies into ganache and place on parchment. Add sprinkles or pipe with colored icing before ganache sets. Allow to cool fully before serving or storing.