Place the chocolate in a microwave-safe bowl and heat in 30-second intervals, stirring between each, until fully melted and smooth.

Pour about half of the melted chocolate into a chocolate bar mold. Tilt and spread the chocolate so it evenly coats the bottom and sides of the mold.

Place the mold in the freezer for about 20 minutes, or until the chocolate is firm.

While the chocolate chills, mix the butter and sugar in a bowl for 1–2 minutes, until light and off-white. Stir in the vanilla extract.

Add the heat-treated all-purpose flour and mix until a thick, slightly dry dough forms.

Mix in the milk and chocolate chips until the dough reaches a classic cookie-dough consistency.

Remove the mold from the freezer and spread the cookie dough evenly over the hardened chocolate layer.

Pour the remaining melted chocolate over the dough, smoothing the top. Return the mold to the freezer until fully set.

Once completely firm, carefully remove the chocolate bar from the mold.

Enjoy immediately, or store in a chilled environment for up to 14 days.