• Make the Dough:
• In a large bowl or stand mixer, combine sourdough starter, buttermilk, sugar, vanilla extract, and eggs. Mix until well combined. If using brown sugar, break up any clumps first and ensure it’s evenly distributed.
• Add flour and salt to the wet ingredients. Mix on low-medium speed (level 2) until dough comes together with no dry flour remaining. If using brown sugar, mix an extra 30 seconds to ensure it fully dissolves.
• Cover and let rest for 30 minutes. This autolyse period allows the flour to fully hydrate.
• Return to mixer on level 2 and add butter chunks one at a time, letting each piece incorporate fully before adding the next.
• Continue kneading for 10-15 minutes until windowpane test is achieved (dough should stretch thin enough to see light through without tearing).
• Leave dough in bowl, cover to make airtight, and let rise until doubled (6-8 hours at room temperature).
• Prepare the Coating and Pan:
• Generously butter a 12-cup Bundt pan, making sure to coat all grooves and surfaces.
• Mix all spice coating ingredients in a medium bowl. If using individual spices, whisk together to ensure even distribution. If using pumpkin pie spice, simply mix with sugars and salt.
• For the pumpkin butter mixture:
• In a small saucepan over low heat, gently melt the butter.
• Remove from heat and let cool for 1-2 minutes.
• Whisk in the pumpkin puree, maple syrup, and vanilla until smooth and well combined.
• Let mixture cool to room temperature before using (it should be warm but not hot).
• Assemble the Monkey Bread:
• Turn risen dough onto floured surface. The dough should feel soft, slightly tacky, and smell pleasantly tangy.
• Divide into 35-40 walnut-sized pieces using a bench scraper or sharp knife.
• Roll each piece into a smooth ball, tucking the seams underneath.
• Working with one ball at a time, dip in the pumpkin butter mixture, then roll thoroughly in the spice coating until completely covered.
• Layer coated balls in the prepared Bundt pan, distributing evenly. Don’t worry about perfect arrangement.
• Drizzle any remaining pumpkin butter mixture over the top.
• Cover with plastic wrap and let rise for 45-60 minutes until puffy and nearly doubled.
• Alternately: Cover well and place the refrigerator over night. Pull out the next morning and allow to come to room temperature for 1-2 hours before continuing to the next steps.

Bake:

• Preheat oven to 350°F (175°C) during the last 15 minutes of rising.
• Remove plastic wrap and bake for 35-40 minutes until golden brown and internal temperature reaches 190°F (88°C).
• If the top browns too quickly, tent with foil for the last 10-15 minutes.
• Cool in pan for 10 minutes, then carefully invert onto serving plate.

Make the Glaze:

• Beat cream cheese with electric mixer until completely smooth and no lumps remain.
• Add pumpkin puree and mix well until fully incorporated.
• Gradually add powdered sugar, beating until smooth.
• Add cream, vanilla, and pumpkin pie spice. Beat until glaze reaches drizzling consistency.
• Drizzle generously over warm monkey bread, allowing it to run down the sides.