Cook kabocha ingredients "A" until tender, mash, and cool to handling temperature. (I use a microwave.)
Combine all bread "A" ingredients and let rise (1st proof). Adjust the amount of milk depending on the moistness of the kabocha. (I used 135 g.)
Punch down the dough and divide it into equal portions.
Form into balls, cover with a damp cloth, and leave them to sit for 20 minutes.
Gently press the air out of the balls and flatten with a rolling pin. Place a spoonful of kabocha filling in the middle, and form into balls. (Make sure to firmly seal the seams.)
With the sealed end at the bottom, lightly press flat. Using a pair of kitchen shears, make 5 cuts into the sides.
Stick a piece of Pretz (or your choice of stem ingredient) into the center. (Be sure to stick it through to the bottom.) Spritz with water, and let rise for 20 to 30 minutes (2nd proof).
Use a brush to coat a layer of milk for glazing, and bake for about 12 minutes in an oven preheated to 390F/200C.
When they turn a beautiful golden brown, they're done.
To make the kabocha filling: Remove the skin, microwave, mash, and mix well with soft brown sugar.
Heat the mashed kabocha in the microwave without wrapping in plastic wrap to cook out the moisture. (Remove from the microwave every 2 or 3 minutes to evenly mix) I cooked mine for 8 minutes.