Assemble the ingredients in the bread pan of your bread machine according to the manufacturer's instructions. Set on dough cycle.
To make the dough by hand:
Combine the buttermilk and sugar in a medium-size saucepan and warm slightly over medium heat. Transfer the mixture to a large bowl and add the yeast. Stir and allow the yeast to proof for 5 minutes.
Add the oil, flours, egg, pumpkin puree, onion flakes, salt, and poppy seeds. Stir to combine well.
Turn the mixture out onto a lightly floured surface and knead for 5 minutes to create a smooth, elastic dough, adding more all-purpose flour as necessary.
Transfer the dough to a greased bowl and turn the dough ball to coat. Allow to rise until doubled in bulk, about 1 hour.
To make the dough in a mixer:
Combine the buttermilk and sugar in a medium-size saucepan and warm slightly over medium heat. Transfer the mixture to the mixer bowl and add the yeast. Stir and allow the yeast to proof for 5 minutes.
Add the oil, flours, egg, pumpkin puree, onion flakes, salt, and poppy seeds. Stir to combine well.
Attach the dough hook and run the machine until the dough ball forms around the dough hook and cleans the sides of the bowl.
Transfer the dough to a greased bowl and turn the dough ball to coat. Allow to rise until doubled in bulk, about 1 hour.
To form the rolls:
Line a baking sheet with parchment or a silpat mat.
When the dough is ready, turn it out onto a floured surface and divide into 16 portions.
Form each portion into a tight round and place them evenly spaced on the prepared baking sheet. Preheat the oven to 350 degrees. Allow the rolls to rise for 30 minutes.
If you'd like, add the optional topping. In a small bowl, combine the beaten egg and water. Brush this egg wash over the rolls. Sprinkle generously with everything season.
Bake the rolls for 15 to 20 minutes or until golden brown.
Cool the rolls briefly on a rack. Serve warm.
Notes
Promptly store leftovers in an airtight container for up to 3 days. To freeze: store the cooled rolls in a ziptop bag. Remove as much air as possible, seal the bag, and store in the fridge.Nutritional values are approximate and based on 1 roll.