1. For the starter add the flour, water, and milk to a small pot and mix until well combined. Heat up and stir constantly until the mix starts to thicken. Cook until the mixture starts to come off the bottom of the pot easily. Take off the heat and let cool down a bit. Melt the butter for the dough and let cool down as well.

2. Crumble the yeast into the lukewarm milk and mix until dissolved completely. Add the flour, salt, Eierlikör, eggs, melted butter, the yeast-milk and the starter to a large bowl and knead for about 10 minutes to get a nice smooth dough. The dough will be quite soft and a bit sticky, but as long as it comes off the sides of the bowl easily with a rubber spatula, all is fine. Cover with a kitchen towel and let rise for about 60 minutes in a warm place until almost doubled in size.

3. Melt the butter for the filling and mix the sugar with the cinnamon. Set aside. Divide the dough into two equal pieces and roll out each on a floured surface to get two rectangles with 18×8 inches (45x20cm). Brush both with the melted butter and sprinkle evenly with the cinnamon-sugar mixture. Roll up from the long sides and cut each roll into 12 pieces. Grease a 9.5×13 inches (24x33cm) baking tin (or use two round 9 inches baking tins). Place the cinnamon rolls in the baking tin, leaving some space in between, cover and let rise a second time for about 45-50 minutes in a warm place.

4. Preheat the oven to 350°F (180°C). Place the baking tin in the lower third of the oven and bake for 20-25 minutes until the rolls get a nice golden color. Take out of the oven and let cool down a bit.

5. Melt the white chocolate and butter for the frosting and mix until well combined. Add the Eierlikör and vanilla extract and mix in. Add the confectioners’ sugar and mix well. If the frosting is too thick, add some heavy cream. Spread the frosting on the still warm cinnamon rolls and serve warm.