I have been cooking the weekly meals for a client that is on a very strict diet where tomatoes or pasta can't be consumed. This made lasagna a tough one to do until she explained just replace the zucchini for pasta and use fresh stock as the sauce. As a chef my concern was that there would be no substance to the sauce but I did as she asked and it was a massive hit but I thought there has to be a better way.
I tried to come up with another solution but didn't have much luck until recently making some pumpkin puree at home. The consistency was good and thought about using this to replace the tomato base.
I pulled up the email with all the allowed foods and pumpkin was there so I was in luck. My only thing now is it wouldn't look so appealing so I wanted to darken the sauce just so it doesn't look so bland, I scanned the list and the only dark ingredient there was beetroot which would do the job, I can add substance and colour. Not only with this dish but stews, braised beef cheeks and anything else that you want a slightly thicker sauce then just the stock. It worked pretty well, slightly over board on the beetroot but here is how I did it.
First thing is wash the beets and wrap in foil. Peel the Squash, remove the seeds and also wrap up.
Once both ingredients are cooked and cool enough to handle peel the beets and puree them together. I would make up a big batch so you can freeze it in smaller portions as making this overtime would be quite time consuming.
Top with a soy milk, rice flour and nuttelex bachamel and bake as usual.