Identify this dessert

The best I can guess is that this dessert is, in fact, a layered flan.
(or other free-standing baked custard, I suppose).

There are a lot of recipes for fruit flans, including passion fruit (with or without lime juice), lemon, raspberry, and others. In that case, the individual recipes would be the key to search for, rather than the whole confection - once the custard mixtures were made, it would not be impossible to somehow layer them into individual molds before setting, for a similar effect as you describe. Very impressive in a restaurant, and efficient enough in time and effort when they can make full batches of each custard, since they end up making many individual portions.

In any case, you would likely have to find recipes for passion fruit flan (you can check for lime juice, or not, as you prefer), and either simply find a recipe you like, or slowly tweak to match the taste you remember.

Just to give examples - here is one for passion fruit and lemon flan, here is a softer but tasty looking no cook version, This one claims an intense enough flavor to not need vanilla (quite the claim), Here's one with lime in the recipe. This is completely different flavors, but shows an example of a layered flan jelly. A pastry case can be omitted (or inversely, added), the flan can still be cooked and set. Caramel can be omitted, possibly replaced by (fruit) syrups after cooking if desired.

Of course, how close this comes to your expectations depends on which recipe you start with and your desired results, but I had some thoughts on tweaking recipes to match your description - no guarantees, it's mostly speculative. It sounds like this dessert of yours was fairly stiff if it was comparable to a brownie - a higher proportion of egg will make a flan stiffer, obviously liquids will make it softer and looser. Using a recipe witch includes pulp (smoothly pureed, for consistency) will probably make a thicker end result than one only flavored with juice. Using cream vs condensed milk vs cream cheese or egg yolks vs whole eggs should help tweak rich and soft versus firmer and drier.

Some recipes are thickened with gelatin, and it may be possible to further thicken the recipe with starch or even flour (if it ends up well cooked) to make a batter, which will get you a bit further afield from most flan recipes, but might help if the texture is not quite what you wanted.

I would be tempted to call it a dessert terrine with a tart shape.