Gently melt together in a saucepan over low heat, the milk, butter, and golden syrup. Pour it in a bowl to cool until it reaches body temperature.
Now you're going to pour the cooled mixture into a stand mixer and stir in the yeast. Let that bloom for 5 minutes.
After 5 minutes, add in the bread flour, Swedish rye sift, salt, and spices. Let that knead on medium speed in the mixer for about 10 minutes, until it is smooth, elastic, and can pass the windowpane test. This is where you stretch a small piece of dough, and if you can see through it slightly and it doesn't rip, your gluten has developed properly.
Place the dough in a covered bowl and let it rise until doubled in size, about 1½-2 hours.
Once doubled, punch down the dough and then roll it out on your work surface until it is about 10-11 inches wide. Fold in the sides and roll it into a spiral, pulling the dough towards the middle of the loaf as your roll so it doesn't end up bigger on the ends. Then scoot your loaf on your surface with two hands to create tension in the loaf. This will help to create better structure.
Place it on your parchment-lined baking tray, cover it, and let it rise until doubled. This may take 30 minutes to an hour.
After it has risen, bake it in a 350℉ / 180℃ pre-heated oven for about 35 minutes. The traditional look of this bread is quite dark with a smooth, unslashed surface. Remove it from the oven and brush it with a couple of tablespoons of golden syrup and let it cool and the surface dry completely before slicing into it. To enjoy it like the Swedish do, eat it with a slice of hard cheese and a glass of cold milk.