Adjust the oven rack to the middle position, pre-heat the oven to 350ºF (180ºC) and line two large baking sheets with parchment/baking paper.
You can prepare the cookie dough either by hand, using a wooden spoon, or using a stand mixer fitted with the paddle attachment on the lowest speed setting.
In a large bowl, mix together the softened butter, sugar and vanilla until well combined and smooth. Don't cream or aerate the mixture.
In a separate bowl, whisk together the gluten free flour blend, cocoa powder, xanthan gum and salt.
Add half of the dry ingredients to the butter-sugar mixture, followed by the milk and then the remaining half of the dry ingredients, mixing well after each addition.
Transfer the cookie dough into a piping bag fitted with a large open star piping tip.
Pipe the cookies into whatever shape you wish, spacing them at least 1 inch apart.
Bake at 350ºF (180ºC) for about 14-16 minutes or until they’re crisp to the touch.
Allow the cookies to cool on the baking sheet for about 10 minutes, then transfer them to a wire rack to cool completely.
Dip half of the cookie into the melted chocolate, then gently shake it to remove any excess chocolate. Place the chocolate-dipped cookie onto a lined baking sheet and decorate with sprinkles of choice.
Allow the chocolate to set completely before serving the cookies.
