Spray a 8.5x4.5-inch loaf pan with baking spray. Set aside. Add the oat milk to a small saucepan. Heat until just warm, 110-120F. In a large bowl, combine the warm milk and yeast. Stir to dissolve. Set aside for about 10 minutes. In a small bowl, combine aquafaba & psyllium husk and set aside to thicken.
To the milk and yeast mixture, add puréed pumpkin, butter, sugar, aquafaba/psyllium “egg”, and salt. Beat with a mixer on medium until just combined. Add half of the flour. Beat on low for about 30 seconds. Scrape the bowl as needed. Beat for 3 minutes on medium, then stir in the remaining flour. The dough should be soft but not overly sticky. Add a little flour as needed.
Shape the dough into a ball; then place in a greased bowl. Cover with a tea towel and let rise in a warm place for about 50 minutes. The dough should double in size.
While the dough is proofing, prepare the pumpkin butter and cinnamon sugar. For the pumpkin butter, in a small bowl, combine puréed pumpkin, melted butter, cinnamon, salt, nutmeg, and clove. For the cinnamon sugar, in a small bowl, combine brown sugar and cinnamon.
When the dough is proofed, turn the dough out on a lightly floured surface. With a floured rolling pin, roll the dough out into a 20x12-inch rectangle. Spread the pumpkin butter, then sprinkle the cinnamon sugar evenly on top of the pumpkin butter. At this point, if the dough is too soft to lift, transfer to the refrigerator for a little to firm up. If not continue on - this is where it gets messy!
Cut the dough into five 12x4-inch strips. Then, stack the strips together on top of one another..
Cut this large stack into five 5x2.5-inch pieces. It’s okay if the measurement are off, just make sure the number of pieces are correct. Transfer the stacks to your prepared loaf pan. It’s okay if they’re not stacked perfectly into the pan, or it’s slipping and sliding because of the filling. Just try your best, and remember that all these imperfections will bake up into a crispy, chewy deliciousness with peaks and valleys. Let rise in a warm place for about 45 minutes or until it about doubled in size.
While the loaf rises, preheat your oven to 350 degrees, and Bake for about 35-45 minutes or until deep golden brown. Watch for any stacks that want to jump out of the pan as it bakes - if so, place a baking sheet on a bottom rack to catch any rogue dough or filling drips. When the loaf is done, cool for about 15 minutes and then remove from the pan.
In the meantime, prepare your cinnamon glaze by whisking to the powdered sugar, cinnamon, vanilla, and salt. Add as much milk as needed, one tablespoon at a time, to create a glaze that can be drizzled.
Transfer the loaf to a serving dish, and drizzle with the prepared glaze. Leftovers can be wrapped and refrigerated, just reheat in a toaster oven or microwave.