When making veg lasagne, do you cook the tomatoes down completely?

[CharCharBaGOOOOOOORE]

Or leave them a bit watery? I was thinking maybe it needed to be a bit more watery to cook the pasta. Or do I just cook it exactly like bolognese? TIA.

I tend to add a tin of toms and puree for liquid, so i end with a lumpy tom and veg sauce if that makes sense.