In a glass bowl, melt chocolate with butter over a saucepan of simmering water. Put aside to cool.
In a large bowl, whisk together the sugar, eggs, and vanilla.
Pour in cooled chocolate mixture (let it sit to room temperature) and whisk until combined.
In another bowl, whisk together the gluten free flour, baking powder and the salt. Stir into chocolate mixture until combined, using a wooden spoon. Stir in chocolate chips. Cover bowl with plastic wrap. Refrigerate for two hours or until firm.
Pre-heat oven to 350°F.
Line one large baking sheet (or two small ones) with parchment paper.
Scoop 1 tbsp of dough and roll into balls. Coat each ball in sugar (put 1/4 cup of sugar in a bowl or on a plate).