Place flour, yeast, caster sugar, salt and cardamom, if using, in a stand mixer fitted with the dough hook attachment. Mix on low speed until combined. Add milk, butter and egg, and mix on low speed until combined.

Increase the mixer speed to medium-high and knead the dough for 10-15 minutes or until smooth and elastic. Gather dough into a ball and place in an oiled bowl. Cover with plastic wrap or a clean tea towel, and set aside in a warm, draught-free place for 1 hour or until doubled in size.

Meanwhile, to make the filling, combine butter, brown sugar and ground cinnamon in a bowl until smooth.

Lightly grease 2 large baking trays and line with baking paper. Use your fist to knock back the dough. Transfer to a surface lightly dusted with extra flour. Shape into a rough rectangle. Use a rolling pin to roll out dough to a rectangle about 50 x 30cm. Gently spread the butter mixture over the dough, all the way to the edges.

Starting at one short end, lift the dough and fold the short end into the middle of the rectangle. Next, fold the opposite short end over the top. Use a rolling pin to flatten the layers together and roll out any air bubbles, then roll out to roughly a 30 x 20cm rectangle.

Use a pizza cutter to cut 2cm-thick strips lengthways down the rectangle. Take 1 pastry strip and twist it several times, gently stretching it as you do so until it nearly doubles in length. Make a coil with the twisted strip, tucking the ends slightly underneath. Place on a lined tray. Repeat with the remaining dough strips, placing the coils 5cm apart on the trays. Cover trays with plastic wrap or a clean tea towel and set aside for 45 minutes or until almost doubled in size.

Preheat oven to 180°C/160°C fan forced. Place extra caster sugar and water in a saucepan over low heat and stir until sugar dissolves. Increase heat to medium-high and bring to the boil. Remove from heat and set aside.

Whisk the extra egg and 1 tbsp milk in a bowl. Use a pastry brush to brush the bun tops with the egg wash. Bake buns for 10-15 minutes or until golden brown.

As soon as the buns come out of the oven, brush the tops with the sugar syrup. Sprinkle with cinnamon sugar and serve warm or at room temperature.