Make the dough: dissolve the yeast in the lukewarm milk. Add the sugar, salt and cardamom, then the flour little by little. Knead for 5 minutes, add the soft butter in pieces and knead for another 8 to 10 minutes, until the dough is smooth, supple and comes away from the sides of the bowl.

Cover with a tea towel and leave to rise for 1 hour in a warm place, until doubled in size.

Make the filling: mix the very soft butter, brown sugar and cinnamon into a smooth paste.

On a floured surface, roll out the dough into a rectangle of about 30 × 50 cm (12 × 20 in). Spread the filling over the whole surface, then fold the dough in three lengthwise, like a letter, to get a strip about 10 × 50 cm (4 × 20 in).

Cut the strip into 20 ribbons about 2.5 cm (1 in) wide. Twist each ribbon, wrap it twice around two fingers, then tuck the end into the centre to form a knot. Place the knots on two baking sheets lined with baking paper.

Cover and leave to rise for another 45 minutes. Preheat the oven to 220 °C / 425 °F (fan 200 °C).

Brush the buns with beaten egg, sprinkle with pearl sugar and bake one tray at a time for 10 to 12 minutes, until golden. Leave to cool on a rack, covered with a tea towel so they stay soft.