Mix the ube powder with the boiling water, stirring thoroughly. Let cool to room temperature.

In the bowl of a stand mixer, add the flour, sugar, and salt, and whisk to combine.

Add the warm milk, oil, and egg, and mix. Add the yeast and knead with the dough hook until combined. Add the ube mixture and the optional extract and knead with the dough hook until combined. The dough should be fairly sticky. Adjust the flour if necessary but don't add too much. Knead for about 8 to 10 minutes.

Transfer the dough to an oiled boil or dough rising bucket, cover with plastic wrap, and let rise until doubled, about 30 to 60 minutes. You can also let the dough rise overnight in the refrigerator.

Heat the oven to 350 degrees F. and line a sheet pan with parchment paper. Place the breadcrumbs into a small bowl.

Deflate the dough and divide it into 12 equal pieces. Flatten each piece of dough into a circle and place the optional filling in the center. Wrap the dough around the filling and form each piece into a ball. Dip the top of the roll in the breadcrumbs. Place the shaped ball, seam side down, on the parchment in a 3 by 4 pattern, about 1 inch or more apart.

Cover the shaped rolls in plastic wrap or a towel and let rise until the rolls are puffy, about 30 to 60 minutes.

Bake the rolls for 20 to 25 minutes. Cool a few minutes on a rack. Serve warm.