Combine the flour, yeast, salt, and 1/3 cup sugar in the container of a food processor fitted with the steel blade and process for 5 seconds. Add the 2 tablespoons butter and the egg and pulse a few times, until well combined. With the machine running, drizzle most of the milk through the feed tube. Process just until a dough ball forms; add more milk, 1 teaspoon at a time, if necessary.
Knead by hand on a lightly floured surface for a minute or two longer, adding a little more flour or milk if necessary, until the dough is silky smooth and elastic.
Butter a bowl; place the dough in it. Cover and let rise until doubled in bulk, at least 2 hours. (Hasten the process by putting it in a warm place.).
Roll out the dough into a 1/2-inch-thick rectangle. Brush liberally with the 4 tablespoons butter (melted), then spread with a mixture of the 1/2 cup of sugar and the cinnamon. If you like, dot it with about 3/4 cup raisins or nuts (I didn't). Roll it up, lengthwise, then cut into 1- to 1-1/2-inch thick slices.
Place in a buttered 12-compartment muffin tin and let rise until puffy, about 1 hour.
Preheat the oven to 400°F.
Brush the tops of the rolls lightly with melted butter and sprinkle with sugar. Bake until nicely browned, about 20 minutes.