Você pode usar farinha de konjac, mas precisará aumentar o pH. Comece com o cacau processado holandês, pois o cacau normal é ácido.
De Guy Crosby (o cara da ciência no America's Test Kitchen):
But even more surprising, when the pH of a viscous 1% dispersion of konjac flour is raised to pH 9-10.5 by the addition of a mild alkali, then heated to about 85° C (185° F) for 20 minutes, and cooled, the sol transforms into a very firm, but elastic heat-stable gel. So stable that it will not melt even when placed in a 177° C (350° F) pan or oven!