If you want to be indulgent with the white sauce, try swapping cream for the milk and throw in ricotta and feta , about 1 part feta to 4 or 5 parts ricotta is a good cheese ratio to balance the sharpness of the feta with the blandness of the ricotta. The white sauce is what makes a lasagne (especially a vegie one!) so experiment and make it unreal.
I usually toss an egg into my cheese/white sauce mix. It just adds- something. Extra fat and calories, I guess.