• Preheat the oven to 200°C.
• In a bowl, mix the flour, the baking powder, the sugar and the butter.
• Mix together with the fingertips to obtain a smooth dough.
• Pour in the milk and mix well. Add the goji berries.
• Roll the dough on a floured work surface. Reduce the thickness by about 3 mm.
• Cut circles out with a shape cutter.
• Put the circles on baking paper. Glaze with the egg yolk.
• Bake for 15 to 20 minutes (if possible without fan-assisted heat) until they are golden and puffy.