As we learned in Darioles, by mid-18thC people were becoming concerned about the necessity of baking in crusts—an added calorie count—and were looking for ways of cooking without having to eat the container. Most modern timbales reflect this continued idea, and are usually layers of cooked pastes or custards, pasta or rice and vegetables and/or meats baked in molds and inverted onto sauces when plated. Ingredients and sauces can be served either hot or cold and are especially tasty when served in season.
As an example, Dione Lucas suggests using lobster coral to line a buttered timbale mold in which to bake an egg. Both she and Julia Child suggest using crepes to line the mold and to fold over the top [which ends up being the bottom when unmolded] to contain savory ragouts.
Dictionnaire Portatif de Cuisine, d'Office, et de Distillation. Chez Vincent, Paris 1767, p. 350.
Name given to any sort of ragout that one locks up in a pie [either a pastry crust or other manner of food used to contain the ragout once it is cooked and will hold its shape when unmolded], & which one bakes in an oven. Only your imagination and your mold limits you in the size or [crust] or filling of your timbale—any kind of ragout can be baked in a [crust] in a timbale.
Nom qu’on a donné à toute espece de ragout qu’on enferme dans un pâté, & qu’on fait cuire au four. On en peur faire, & imaginer d’autant de façons qu’il y a de sorte de ragouts, qui peuvent se mettre en pâté.