You can do this in advance so it has time to cool.

In a saucepan, heat milk and cream. Remove from heat.

Note: If you don’t have heavy cream on hand, you can use 250 ml of whole milk instead. The custard will be slightly lighter in texture but still smooth and tasty. If using a vanilla pod, split and scrape it, then add both seeds and pod to the milk-cream mixture before heating.

In a bowl, whisk egg yolks, sugar, and cornstarch until smooth.

Slowly pour the hot milk mixture into the yolks while whisking constantly.

Return everything to the saucepan and cook over medium heat, stirring constantly, until thickened.

Remove from heat, stir in butter until smooth.

If using vanilla paste, stir it in at this stage for the best flavour.

Cover with plastic wrap, touching the surface to prevent skin from forming and letting it cool completely.

Refrigerate till use.

In a small saucepan, combine blueberries, sugar, and cornstarch. Cook over medium heat.

Gently mash the blueberries with the back of a spoon to release their juices.

Cook over medium heat until the mixture thickens and bubbles.

Let it cool completely before using.

In a large bowl or stand mixer, combine the flour and salt. Mix well before adding the rest of the ingredients.

Add the sugar, vanilla sugar, ground cardamom kernels, instant yeast and egg. Mix to combine.

With the mixer on low speed, gradually add lukewarm milk (start with 250 ml) until a soft dough begins to form. Add more milk if needed.

Knead the dough on medium speed for about 5–7 minutes until it comes together.

Add the softened butter in pieces, a little at a time, and continue kneading for 8–10 minutes, until the dough is smooth, elastic, and slightly tacky.

Cover the bowl with a kitchen towel or plastic wrap and let the dough rise in a warm place for about 1–1.5 hours, or until doubled in size.

Punch down the dough and turn it out onto a floured surface.

After the dough has risen, divide it into two equal parts (approximately 510 g each). Shape each portion into a smooth ball.

Take one portion of dough (keep the other covered to prevent drying out) and roll it into a rectangle on a lightly floured surface.

Spread half of the cooled vanilla custard evenly over the dough.

Spread half of the blueberry filling over the custard.

Starting from the long side, roll the dough into a log. Pinch the seams and ends to seal.

Cut the log into equal pieces.

Place each piece into a muffin tray lined with paper liners, cut side up.

Take the second portion of the dough and roll it into a rectangle.

Spread the remaining custard and blueberry filling evenly over the surface.

Fold the dough in half along the long side to enclose the filling.

Gently roll over the dough to even it out.

Use a pizza cutter or sharp knife to cut the dough into strips, each about 1 cm wide.

Take one strip, gently stretch it, and twist the ends in opposite directions to create a spiral.

Wrap the twisted strip into a bun shape, tucking the end underneath.

Repeat with all strips, shaping each into a neat knot.

Place shaped buns on a parchment-lined baking sheet.

Watch the video above to see how I am shaping each bun.

Cover the filled buns lightly with a kitchen towel. Let rise for another 30–45 minutes.

Preheat the oven to 200°C.

Brush the buns with egg wash (1 egg + 1 tbsp milk or water), avoiding the filling.

Bake for 15–20 minutes or until golden brown.

Brush the buns with melted butter or sugar syrup.

Let cool on a wire rack.