This looks interesting. I’m not even sure what a roulade is but I do have some wood smoked salmon in the fridge and spinach so that’ll be perfect. I made a large flat baking dish out of tinfoil 33x37cm and brushed it with butter. 
The next step was to make a nice thick white sauce with butter, flour and milk into which I flaked the smoked fish. Speaking of decadent food, I went to Little & Friday recently and wow their food is spectacular. Great baking, good value, donuts to die for. It’s one of those bakeries where you can’t not buy something. http://www.little&friday.com
I separated the eggs and stirred the yolks into the fish with chopped parsley. Then I whisked the whites till they were at stiff peak stage. 
These were then folded into the white sauce with fish and I spooned this mixture into the prepared dish.
This was baked and came out light and fluffy.
The filling was made with another white sauce to which I added
cooked spinach and grated parmesan. I spread the filling over the cooked base and rolled it up.
This was delicious, so smooth and rich. It was like a souffle. It paired really well with fresh coleslaw. Great dinner!! I would make this again, so yum. 
