I had a wonderful torte at a Superbowl party that had a base made from a flour-stabilized meringue (1 T flour + 1T sugar for each egg white) which is like an angel food cake with way too much egg white. There were hazelnuts embedded in the base layer which were then covered with Nutella, then a layer of vanilla custard, followed by a layer of chocolate custard, and topped with a layer of whipped cream. When I asked how to make it I was referred to recipe for Monte Torta:
and the fact that the site is in Croatian adds a certain degree of difficulty without making it totally impossible. After some study, the vanilla and chocolate custard layers appear to be made from a buttercream stabilized, cornstarch-based, commercial vanilla pudding with added egg yolks; half of it has chocolate added to make the second layer.
While I am not totally against using buttercream, if I am going to make this more than once a year I need to develop a formulation with less fat. My thinking is to continue to base the custard on a commercial pudding mix (Jell-O cook & serve, made with 2/3 the liquid called for, and using water instead of whole milk, and adding some citric acid to the vanilla half so that it becomes lemon curd). The resulting pudding without the added buttercream is a little soft. So I am looking for a way to firm it up by adding a hydrocolloid with or without whipping. The top layer will probably change from straight whipped cream to a Bavarian cream for a little different mouth feel.
The reason for this post is to see if anybody has suggestions on specific formulations of hydrocolloid additions that might serve the purpose. Options I have thought of but not yet tried include gelatin, pectin (regular but more likely low methoxyl), agar, and locust bean gum synergized with xanthan gum.