Preheat the oven to 175°C/fan 155°C. Butter and line two 1.5L loaf tins with baking paper.
Crush the seeds in a mortar and set aside.
In a large bowl, combine the flours, crushed seeds, bicarbonate and salt. Whisk together to combine. In another bowl, mix the syrup(s) and filmjölk; pour over the flour mixture and mix using a silicon spatula until barely smooth.
Divide between the two prepared tins and generously sprinkle with coarse rye flour.
Bake in the preheated oven for 1h30, at which point the core temperature of the loaf should read 96-98°C.
Allow to cool down in its tin for 10 minutes, then unmould onto a rack and leave to cool down completely to room temperature. Wrap in clingfilm.
The loaves will keep in the fridge for up to two weeks, or in the freezer for a month or two, although the latter tends to make the crumb slightly drier.