In a large mixing bowl, whisk together your sourdough discard, warm milk, granulated sugar, and melted butter. Allow this mixture to sit for about 10-15 minutes until it becomes bubbly and slightly frothy.

Add all-purpose flour, cinnamon, and a beaten egg to the bubbly mix, stirring until a shaggy dough forms. Knead the dough for about 8-10 minutes until it feels smooth and elastic.

Place the kneaded dough in a greased bowl, covering it with a clean kitchen towel. Let it rise in a warm area for 1-2 hours, or until it's doubled in size.

Once the dough has risen, roll it out to a rectangle roughly 12x18 inches. Spread softened butter evenly, then sprinkle with brown sugar and cinnamon.

Starting from one edge, roll the dough tightly into a log shape. Slice the dough into 1-inch thick sections.

Place the sliced rolls into a greased 9x13-inch baking dish, ensuring they are touching but not overcrowded. Cover and let them rise for about 30 minutes.

Preheat your oven to 350°F while the rolls are rising. Bake for 25-30 minutes or until golden brown.

Prepare the cream cheese glaze by blending softened cream cheese and powdered sugar until smooth. Drizzle generously over warm rolls.