Open cardamom pods and crush seeds in a mortar and pestle or electric spice grinder until fine.
Pour milk into a pan. Add cardamom and gently heat until around 45 degrees.
In the bowl of a stand mixer or in a large mixing bowl, briefly mix sugar, yeast, salt, butter, and egg. Don't worry if the butter is still a bit lumpy.
Add milk and cardamom, mix briefly and add most of the flour.
In a stand mixer, user the dough hook and knead for a few minutes until the dough is glossy, smooth and soft. Alternatively, knead by hand for five minutes. The dough should be a little sticky. Don’t add too much flour at once, as you don’t want to end up with a dry or hard dough.
Cover the bowl with the tea-towel and leave the dough to proof until doubled in size.
In the meantime, make the filling: Mix all three ingredients until well combined and smooth.
Once the dough is well risen, tip it onto a floured work surface and divide it in two.
Roll half the dough into a large rectangle and spread half the filling on top, covering the whole rectangle.
Fold the dough into three like a business letter (fold the top long side down to the middle, then fold the bottom long side over the top).
Cut the dough into 2cm strips, then cut every strip down the middle, leaving one end intact (so they look like a pair of trousers). Twist the two “legs” into a knot (this does not have to be very precise, you can go a bit freeform).
Place the buns on a parchment-lined baking sheet, cover with a tea towel, and leave to rise until almost doubled in size, about 40 minutes. Repeat with the other half of the dough and filling.
Preheat the oven to 200° C. Brush the buns with lightly beaten egg and bake for about 10 minutes or until golden.
Brush the still-warm buns with golden syrup mixed with water and sprinkle with ground cardamom mixed with superfine sugar.