Preparation steps for the evening prior:

In a mixing bowl, combine 1 stick cold butter (grated using a cheese grater), sourdough starter discard, buttermilk, sugar, and salt. Blend the ingredients using a spatula until they are well incorporated.

Add the flour and using your hands or a dough hook with a stand mixer, kneed the mixture into a stick but smooth dough ball.

Add the dough to a greased bowl and let it rest on the counter overnight (10-12 hours).

Morning preparation steps:

Preheat the oven to 375°F (190°C) and grease a deep 11x16 baking dish.

Create the leavening agent mixture by combining the baking powder and baking soda in a small bowl using a fork until the mixture is free of lumps. Spring the dough with the mixture and kneed it in before rolling out the dough.

Roll the dough out on a floured workspace and rolling pin, creating a 12" x 24" rectangle.

Mix the remaining softened butter with the brown sugar and cinnamon, then spread it across the dough.

Roll the dough into a log and slice it into 12 pieces, placing each piece in the baking dish with some space for expansion. Let it rest for 1 hour.

Bake for 35-40 minutes in the preheated oven until the tops are golden brown.

As the cinnamon rolls bake, mix the ingredients for the frosting. Apply the glaze to the hot rolls once baked.

Let cool and then enjoy!