1) Mix and knead all of the dough ingredients to make a smooth, soft dough.
2) Let the dough rise, covered, for 1 hour.
3) Place 12 mini-panettone papers on a baking sheet. Or line a standard muffin pan with cupcake papers, and grease the papers.
4) With greased hands, divide the sticky dough into 12 equal pieces, forming each into a smooth ball.
5) Place the balls of dough into the papers. Cover the pan, and let the cakes rise for 1 hour. Towards the end of the rising time, preheat the oven to 350°F.
6) Whisk the reserved egg white with 1 tablespoon water, and brush it over the cakes.
7) Bake the cakes for 20 minutes, then tent them lightly with aluminum foil and bake for an additional 20 to 25 minutes, until they're a deep golden brown. Remove them from the oven, and transfer to a rack to cool.
8) Beat together the icing ingredients, dribbling in the final teaspoon of milk until the icing is thick yet pourable.
9) Dip the top of each cake in the icing, or drizzle icing over the tops of the cakes. While the icing is still tacky, sprinkle with the colored sugars.
Yield: 12 cakes.