Pour the sourdough culture into a large mixing bowl. Stir in the milk, vanilla, salt, and 2 tablespoons of sugar and mix well using a Danish dough whisk or wooden spoon. Add the flour a cup at a time and mix until you have a shaggy dough.

Turn the dough out onto a floured surface and knead in the remaining flour until the dough is smooth and satiny.

Place the dough in a large, clean bowl and cover the bowl with plastic. Let it proof in the refrigerator overnight (8 to 12 hours).

The next day, let the dough warm up to room temperature (an hour or so) and then gently transfer it to a floured surface. Let the dough rest on the counter for 30 minutes.  If it flattens a lot during this time, add in additional flour before rolling the dough out.

Roll the dough into a rectangle, about 1/2 inch thick. Brush it with melted butter. Mix together the cinnamon and sugar and sprinkle the mixture over the top of the dough. If you want to add raisins, now is the time to do it.

Starting from the long end, roll the rectangle up into a log.

Cut the log into 1-inch thick rolls using a knife or floss. Place the rolls close together on a baking sheet or in cake pans and proof for an hour or until doubled in size. Depending on the temperature in your kitchen, it could take longer than an hour.

Bake the cinnamon rolls in a preheated 350 degrees F. oven for 25 to 35 minutes. Watch the rolls to make sure they don’t burn on the bottom.

Remove the rolls from the oven, and while they are still hot, drizzle the powder-sugar glaze over them.

Carefully remove the rolls from the pan and serve them warm.