Test Kitchen Tips:
• Biscoff Cookies are a brand of Belgian speculoos cookies. These crisp cookies have flavors of caramel and spices. Find them in gourmet markets, the international or cookie aisle of some supermarkets or online stores. If unavailable, substitute crushed gingersnaps.
• Do not reroll bao dough more than once. Overworking dough may cause bao buns not to rise properly.
• If you have a traditional bamboo steamer, use it to steam the bao buns. If you own neither a bamboo steamer nor a steamer basket, you can use a metal colander. You can also make a steamer out of a disposable aluminum cake pan. Poke holes in the bottom of the cake pan. Place upside down in large pot with 1/2- to 3/4-inch boiling water. Place parchment paper on the pan. Place some of the bao buns on the parchment paper. Cover and steam as directed.