trying to recreate a recipe (salmon pizza)

A couple weeks ago, we were in Toronto and ate at a place called Pizza Rustica. We each had a different kind of pizza and I’m trying to re-create the one I ate, because everyone loved it.

It definitely had:
-salmon
-capers
-red onion
-a creme fraiche w/dill topping

All of which is very common to the recipes I’m finding online, but it also had some kind of a white sauce beneath the main toppings.

Unfortunately, the restaurant doesn’t have the exact description posted online. The white sauce was probably baked with the pizza and the other toppings added afterwards. I seem to recall that there was some type of cheese (goat cheese, feta, mozzarella?) in the sauce.

Any thoughts on how to re-create this or what might have been in the sauce? Recipe ideas?

I found a Pizza Rustica in Georgia that offers a white pizza with onions, goat cheese, and smoked salmon. There’s another in Philadelphia that includes salmon roe (and flakes of 24k gold).

Here’s a basic white sauce for pizza.

mmmmm… that sounds really tasty