Beginning with a recently fed, active starter, add the sourdough starter, sugar (1/3 cup), warm water, melted butter (6 tbsp), salt, and flour (4 cups) to the bowl of a stand mixer with a dough hook attachment.

Mix for 10-15 minutes at medium speed using the dough hook, until the dough is smooth and stretchy.

Check gluten development with the windowpane test: When you stretch a small piece of dough thin enough, light should pass through it like a pane of glass without tearing. If it tears immediately, run the mixer for another two minutes and test again.

Place the dough in a large greased bowl and cover with a lid or plastic wrap.

Allow to ferment overnight (8-12 hours) at room temperature.

The following day, turn the cold dough out onto a lightly floured work surface.

Divide the cold dough into eight equal parts. Divide again until you get about 32-40 equal sized pieces.

Shape each piece of dough, creating tension against the countertop by rolling it in a circular motion with your palm.

Prepare the cinnamon sugar mixture by stirring 1/2 cup sugar and 2 teaspoons cinnamon in a medium-sized bowl or gallon-sized bag.

Roll each of the dough pieces into the cinnamon sugar mixture, then layer them into a greased bundt pan (a 10-cup pan is ideal).

Cover the pan with plastic wrap and let the dough rise for 1-2 hours or until doubled in size and soft to the touch.

Preheat oven to 350 degrees.

In a small saucepan on the stovetop, melt 1/2 cup butter and whisk in 1 cup brown sugar until just dissolved. Pour evenly over the top of the rolls.

Bake at 350 degrees for 40-50 minutes. The monkey bread should be golden and bubbly.

Remove from the oven and turn over onto a serving platter while still hot (flip decisively while holding the platter firmly against the pan top).

Combine powdered sugar and milk until a smooth glaze forms.

Drizzle the glaze over the warm monkey bread. Serve and enjoy right away!