Fill 2 cups of water into a medium-sized saucepan and bring it to a boil. Place the Hokkaido pumpkin chunks into a steaming basket and steam for about 20 minutes.
Transfer the steamed Hokkaido pumpkin chunks into a flat bowl and let cool to room temperature. Meantime prepare the predough.
In a big bowl, mix 2/3 cups of white spelt flour with 1/2 cup of water, yeast and brown sugar. Cover with clingfilm and let proof for about 30 minutes at a warm place.
Transfer the steamed Hokkaido chunks to a blender and mix on medium speed until you get a smooth puree. You might have to scrape the sides multiple times.
Now combine all the ingredients in a big bowl including the predough and knead for about 2 minutes. The dough is slightly wet, don't add more water, just lightly flour your work surface. Divide the dough into 6-8 even portions and shape them into balls, about 6 ounces per roll. You get the nicest shape when you tuck the dough from the top underneath the ball (2-3 times) and then rotate it on the work surface with your hand shaped like a claw. At the end of the proofing time, preheat your oven to 400°F/350°F fan that's 200°C/180°C fan.
Place them on a parchment paper-lined baking tray, cover with a towel to prevent the build-up of a skin and let proof in a warm location for about 30 minutes or until the size of the balls has doubled.
Get four 30-centimetre long pieces of kitchen string for each roll and tie them to a knot in the middle. Place the roll on top and tie together the strings from opposite ends. See second method above.
Brush the rolls with milk and bake for about 25 minutes.