In a large bowl, combine the sourdough starter, milk, sugar, melted butter, vanilla extract, and salt. Mix well.
Gradually add the flour, one cup at a time, until a soft dough forms.
Knead the dough on a floured surface for about 5-7 minutes until smooth.
Place the dough in a greased bowl and cover it with a cloth. Let it rise for about 1-2 hours or until doubled in size.
Preheat the oven to 350°F (175°C).
Roll out the dough into a rectangle, approximately 1/4 inch thick.
Spread softened butter over the dough, then sprinkle brown sugar and cinnamon evenly.
Add raisins or nuts if desired.
Roll the dough tightly from the long side and slice into 12 equal pieces.
Place the rolls in a greased baking dish and let them rise for another 30 minutes.
Bake for 25-30 minutes until golden brown. Allow to cool slightly before drizzling with cream cheese frosting.