Grind the saffron threads as finely as possible using the back of a spoon or if you have one, a mortar and pestle. Warm up about 57 ml (1/4 cup) of milk and pour over the saffron, stirring well. Leave this to steep/dissolve for at least 1-2 hours, until the majority of the saffron has dissolved. You may have to reheat the milk to keep it warm which will help it dissolve a little faster.
Heat the remaining milk, in the microwave or a saucepan, until it is “fingervarm” (finger warm), meaning it should feel warm to the touch but not hot. Add your yeast and 1 tbsp of sugar, stir, and leave it for 5-10 minutes until the mixture starts to bubble up, meaning your yeast is alive and not expired.
Add the salt, remaining sugar (5 tbsp), saffron mixture, egg, and egg yolks to a large bowl and mix well. Once the yeast mixture has bubbled up a bit, add it to the egg mixture. Mix well.
Slowly add the flour and softened butter, mixing with a wooden spoon until the dough starts to come together.
Knead until smooth and elastic, about 10 minutes. Add more flour if the dough is too sticky; it should be soft and smooth, not too sticky nor too dry. Use a stand mixer if you would prefer!
Cover the dough with cling film or a clean dishtowel and let rise for about an hour or until doubled in size.
Once the dough has doubled in size, divide into 16 equal sized pieces.
Begin shaping the buns by rolling out each piece into a log.
Then, curl one end inward until you reach the middle.
Repeat the same thing with the other end but curl in the opposite direction (see photo for visual explanation!) Repeat until you have 16 Lucia buns.
Place the buns on a prepared baking sheet lined with parchment paper or a silicone mat and cover to let rise for another 45 minutes to an hour until doubled in size. Meanwhile preheat the oven to 410 degrees F (210 degrees C).
Once ready, make an egg wash by combining an egg with a little bit of water and whisking together.
Brush the buns with the egg wash and place a raisin on top of each swirl (2 per bun). You can also top with pearl sugar, but this is optional!
Bake for 10-12 minutes until the buns are lightly golden. Enjoy these sweet rolls with a cup of tea or just on their own!