The spinach could be a riff on spinach florentine
Squeeze out the moisture from frozen spinach, saute onions [shallots] and garlic and add spinach, quick cook and layer on the bottom of the dish [a little red pepper flake would be nice] The butter sauce on the side is a nice deconstruction vs adding some in the dish, and lets you add calories / richness as you like [I'd save some for the baguette!]
Lots of options

J&B