Can you see the top layer? That's an element that you can find in many dishes of Catalan cuisine: the picada.
The word picada means "pounded" or "crushed", since it is made by pounding nuts, herbs, and more in a mortar. Then, the crushed mix is added to a more elaborate dish when it's near the end of its cooking time, so it will cook together adding flavour, making the broth/gravy thicker, and making all the solid and liquid elements of the dish come together more nicely.
Picades are commonly used in meat, fish, vegetables, legume, rice, and soups, making it one of the essential techniques of Catalan cuisine. Almond-based picades, like the one in this photo, are a common element in Catalan food since at least the Middle Ages, as it can be seen in Medieval Catalan recipe books.
There are many types of picades, but some of the most common ingredients are the following. The picada should have a combination of different elements:
Hard elements: toasted almonds or hazelnuts, pine nuts, toasted or lightly fried bread (bread from a couple days ago that has gone hard might be reused for this purpose), or carquinyoli (hard almond biscuit).
Flavourful herbs, spices, or others: garlic, fresh parsley, ñora pepper (dry kind of pepper), black pepper, saffron, cinnamon, chocolate, anchovy, cooked liver, dry orange peel.
Liquid: broth (from the dish you're cooking or other stock), olive oil, ratafia (herbs alcohol), ranci wine, hot water.
You can see an example of how it's made in this video from a Catalan recipe YouTube channel.
Photo of the dish by Turisme Urgell.