Warm 1 cup of milk over low heat until just warm, then mix with 4 tablespoons melted butter.

In the same bowl, stir in 1 cup sourdough discard, ¼ cup sugar, 1 large egg, and 1 teaspoon vanilla extract until smooth.

Gradually add 3 cups flour and 1 teaspoon salt; stir to form a sticky dough.

Knead dough on a floured surface for 5-7 minutes until smooth and elastic.

Place dough in a greased bowl, cover, and let rise in a warm place for 2-3 hours.

Roll the risen dough into a 12x16 inch rectangle, about ¼ inch thick.

Spread 4 tablespoons melted butter over the dough; sprinkle with ½ cup brown sugar and 2 teaspoons cinnamon.

Roll the dough tightly from the long edge and slice it into 12 rolls.

Place sliced rolls in a greased baking dish and let rise for another hour.

Preheat oven to 350°F (175°C) and bake rolls for 25-30 minutes until golden brown.

Prepare frosting by blending 4 ounces cream cheese, 2 tablespoons softened butter, 1 cup powdered sugar, and 1 teaspoon vanilla until smooth.

Frost the warm rolls after baking and serve fresh.