Place butter, salt, brown sugar, and white sugar in a bowl. Beat on speed 5 for 1 minute until soft, creamy, and fluffy.

Add egg yolks and vanilla extract. Beat for 1 minute until well incorporated.

Add baking powder, rice flour, and half the all-purpose flour. Beat until no flour is visible, then add the remaining all-purpose flour and beat until incorporated.

The mixture will be fairly lumpy and thick. If you press it between your fingers, it should stick together rather than being dry and crumbly.

Use a wooden spoon to stir the chopped dark chocolate through the dough.

Tip the dough onto a work surface, then press it together into a 9-inch (22cm) log. Wrap tightly in plastic wrap, twisting to seal the ends.

Refrigerate the dough log for 1.5 to 2 hours.

Baking instructions: Preheat your oven to 350°F (175°C). Slice the chilled dough into ½-inch thick rounds. Place on a baking sheet lined with parchment paper, leaving space between cookies. Bake for 10-12 minutes, or until the edges are golden brown and the centers are still slightly soft. Let cool on the baking sheet for 5 minutes before transferring to a wire rack.