Mix together the butter, sugar and cardamom to make a smooth paste. Set aside.
Shaping the dough: On a lightly floured surface, roll the dough out into 75x40cm. Spread the cinnamon butter mixture on approximately half of the surface. Fold the dough in half, then roll again gently to make an approximate rectangle measuring 45x30cm.
Cut the dough into roughly 2.5cm wide strips, I find a pizza cutter good for this job. Twist each strip several times, slightly stretching it as you do so. Cut another strip in half and coil it round the bun, tucking the ends underneath. Continue with the rest of the strips.
Arrange the buns on a baking sheet lined with parchment paper (if they’re too crowded, use 2 sheets), keeping as much space between them as possible. Cover and leave to prove for 40–60 minutes or until doubled in size, depending on the room temperature.
Meanwhile, set the oven shelf to the middle position and preheat to 190℃ Fan.
Brush the buns with an egg wash, sprinkle with sugar nibs, and bake for 10-12 minutes or until golden brown. Allow the buns to cool on the baking sheet for 5 minutes, then transfer to a wire rack to cool completely.
Best eaten on the day of baking; however, they freeze well for up to 3 months. After defrosting, just warm through in a medium oven for 5–8 minutes.