You could do some capsicums stuffed with a tomato mix similar to a bolognaise but done with lentils. I often do a meat based version and they freeze quite well. The trick is long roasting so the capsicum

You could do a veggo shepherds pie, topped with a sweet potato/potato mash.

I don't know about the roast veggies but we often make a whole head of cauliflower cheese, and freeze the leftovers.