Peel the kabocha and sweet potato. Cook the peeled kabocha and sweet potato and mash them.
Put mashed kabocha pumpkin and sweet potato in a small saucepan, add sugar and stir constantly on low heat for about 5 minutes. When the water evaporates a little and the paste thickens, turn the heat off and cool it down completely.
Make it into small balls (about 2 tbsp each) and set aside.
Pumpkin Bread
Place bakers flour, salt in a large bowl and make a well in the middle.
Combine 1 egg yolk, 150ml milk (to make 160ml all together, so you may need a bit more than 150ml milk), 30g mashed Kabocha pumpkin, sugar, and melted butter and dry yeast.
Pour the liquid ingredients into the well in the flour bowl and mix.
Knead the bread dough for about 20 minutes.
Spray the surface of the bowl and place the kneaded dough and wrap with cling wrap. Leave it for 40 minutes to rise.
Soak the twine (strings) in 1 tbsp of oil (any type of oil is fine, I used olive oil)
When it becomes twice in size, take the dough out of the bowl and divide it into 8 round balls.
Flatten the dough ball out and place pumpkin anko paste on the centre and wrap it.
Take the excess oil off the string and place it on the kitchen bench. Place one dough on the centre. Take two ends of the string and cross it in the centre, and flip the dough around and cross the string, and flip the dough with the string again and repeat. Try not to tie the twine too tight. Make the knot and place the knot side down on the baking paper.
Repeat the step for each.
Place a moist tea towel over the bread and leave it in a warm place for about 30 minutes.
Preheat the oven to 180 degrees celsius and bake them for 12-15 minutes.
Cool the bread down and cut the twine at a few places then remove the twine carefully.
Notes
Kabocha an paste- if you can not access Kabocha pumpkin, you can replace it with purple sweet potato.For the bread, you can replace kabocha pumpkin with butternut pumpkin.