In one of the most popular cookie-decorating videos on YouTube — Amber Spiegel’s “How to Pipe Filigree,” with 1.4 million views — a conical silver tip lays a thread of periwinkle icing onto the surface of a round sugar cookie. Watching one quickly leads to others: winter trees speckled with snow; panda bears with red heart bows; tiny bowls of ramen, complete with fingernail-size hard-boiled eggs and fish cake with a pink spiral center. YouTube reports that more than 10,000 videos on
