Bolu kukus is considered a type of kue bolu, which encompasses a variety of sponge cakes, cupcakes and tarts. The term bolu derives from the Portuguesebolo to generally describe a cake. The texture is thus soft and fluffy just like a tart or chiffon cake. Bolu kukus is a steamed tart instead of a commonly baked cupcake. The bolu kukus base is, however, usually covered with a corrugated paper container, just like common cupcakes.