Warm the Milk & Melt Butter: Warm milk (don’t boil) and melt butter. Combine in large bowl.
Mix the Dough: Add sourdough discard, sugar, egg, and vanilla. Whisk until smooth. Add flour and salt. Mix, then knead until dough is soft and elastic.
First Rise: Cover and let rise at room temp 2–3 hours (or longer if cool) until nearly doubled.
Roll Out the Dough: On a floured surface, roll dough to a 12x16-inch rectangle.
Spread Filling: Brush with melted butter, sprinkle cinnamon and brown sugar. Press lightly.
Shape & Slice: Roll up tightly from the long edge. Slice into 12 rolls using dental floss.
Second Rise: Arrange in greased baking dish, cover, let rise 1–2 hours until puffy (or overnight in fridge).
Bake: Bake at 350°F (175°C) for 25–30 minutes until golden.
Make Cream Cheese Frosting: Whip cream cheese, butter, powdered sugar, and vanilla. Spread over warm rolls.
Serve: Enjoy warm. Store leftovers airtight.
