What can I put in a pasta bake?

[BikeRunSki]

DH doesn't like tuna or prawns, I don't eat meat. What else "substantial" (apart from veg) could I put in a pasta bake, so I don't have to make 2?

I do bacon, mushroom and either leek (my preference) or broccoli (everyone else's). In a white sauce, topped with breadcrumbs and lots of cheese.

lentils or chickkpeas usuaaly feature in ours