For the cinnamon roll dough

1. Add all the ingredients to a stand mixer with the dough hook attached or a large bowl. Mix until combined. Knead the dough for 5 minutes, until you’re left with a soft dough. If the dough is too wet, add more flour, and knead until it’s no longer sticky. If the dough is too dry, add a splash of milk, and knead until it forms a smooth dough.
2. Cover the bowl with a towel and set it aside in a warm spot for 2 hours, or until the dough has doubled in size.

For the cinnamon filling

1. Combine sugar and ground cinnamon in a small bowl.
2. Sprinkle some flour over a clean surface. Scoop the dough onto the surface and roll it out into a large rectangular shape.

Assemble the sourdough rolls

1. Use a pastry brush to spread the melted butter or margarine all over the dough, ensuring that it reaches the edges. Sprinkle cinnamon sugar, rubbing it into the surface of the dough with your fingers.
2. If your dough is too soft to roll, allow it to chill in the fridge for at least 10 minutes. Start from the long side, and tightly roll the dough into a large tube. Use a sharp knife to cut even rolls out of the dough.
3. Place these rolls on a baking tray, leaving a gap between each roll. Cover the tray with a towel, and let them rise for at least 1 hour. Once you’re ready to bake, preheat the oven to 350 degrees F.
4. When the oven is nice and hot, bake the rolls for 20 minutes. When ready, the rolls should be a nice golden brown. Remove the cinnamon rolls from the oven and set them aside to cool.
5. Meanwhile, whisk all of the frosting ingredients in a small bowl until smooth. Add a generous drizzle of frosting onto the rolls.