How do you get a thick, clingy béchamel for Egyptian Macarona Bechamel?

I tried making Egyptian Macarona Bechamel last night, baked pasta layered with spiced minced meat and a creamy white sauce, topped with cheese. Flavor-wise it was spot on, but my béchamel ran straight off the pasta and the cheese on top turned a bit rubbery.

Has anyone here mastered this dish? What tips do you have for:

Thickening the béchamel so it clings (more roux, egg yolk, less milk?)

Picking/melting cheese that browns beautifully without bouncing back under the broiler

Would love your pointers before I dive back in!

I took the base recipe from here for anyone who wants it: https://www.chocolatesandchai.com/egyptian-macarona-bechamel-recipe/