In a large bowl, dissolve the yeast in the warm milk. Stir in 1 tablespoon of the 1/2 cup sugar and the olive oil. Set aside until foamy, about 10 minutes.
Whisk the egg yolks into the yeast mixture until well blended. Whisk in 1 cup of the flour, the rest of the 1/2 cup sugar, and the salt. Cover with plastic wrap and let stand in a warm place for 1 hour.
Whisk in the remaining flour 1/2 cup at a time, switching to a wooden spoon when necessary, until too stiff to stir. Turn the dough onto a floured work surface and knead until smooth, about 5 minutes, adding more flour 1 tablespoon at a time as necessary if the dough is sticky.
Place the dough in a lightly oiled bowl and turn the dough to coat it. Cover the bowl with plastic wrap and let the dough rise in a warm place until doubled, about 1 hour.
Divide the dough into 12 portions, shaping each into a ball. Place each ball in a muffin cup and let rise in a warm place until doubled, about 1 hour.
Preheat the oven to 375 degrees F. In a small bowl, whisk the egg white and sugar just until the sugar is dissolved. Set aside.
Bake the rolls for 18 to 20 minutes, or until golden. Remove from the oven and brush with the egg white mixture while still warm. Let cool in the pan.
To serve, slice in half and fill with a scoop of sorbetto.
Reprinted with permission from "Gelato!: Italian Ice Creams, Sorbetti and Granite" by Pamela Sheldon Johns. Copyright 2000. Ten Speed Press, Berkeley, CA.