Crumble the yeast into the dough bowl and mix it with a little bit of milk. Melt the butter, add the milk and heat both a little above room temperature. Add the mixture to the yeast and stir in 500 g of flour, salt, sugar and cardamom. Next, gradually stir in the remaining flour. Knead everything together into a dough – until it is firm, smooth, homogeneous and no longer sticky. Knead in a little more flour if necessary. Let the dough rise until it has doubled in size (40 min).
After rising, knead the dough again briefly in the baking bowl. Then lift it onto a work surface dusted with a little flour and knead it until smooth. Roll out the dough into a rectangle about 1 cm high. Spread the dough rectangle with the filling and roll it together. Cut the dough roll into slices about 2 cm thick (makes about 14 kanelbullar) and place them on parchment paper on a baking tray. Cover everything together and let it rise for another half hour. Set the stove to 225 °C and stir the filling together. After rising, brush the slices all around with the egg whisked with a little bit of water and bake them in the oven for 10-13 min. Let them cool under a kitchen towel. Kanelbullar taste best when still warm with enough coffee.