Corgette pasta! slice thinly lenthways with a veg peeler or mandolin, and boil for about 2 minutes, yum. Or you could try some of the "Slim Water" type pasta/noodles but they can be expensive
Loads of spinach (I prefer babyleaf) microwaved carefully without water to get it just right (40 secs?), with grated cheese on top and a dash of double cream. And lemon juice on the sauce.
NB I believe passata is more carby than tinned or fresh tomatoes.
make cauliflower rice (grate or blitz in blender or with a stick blender until rice grain size then fry in a pan)
or cauliflower or celeriac mash make in same way as you would mashed potato, don't worry the rice and mash don't really taste like cauliflower.
or make a almond flour based crumble/gratin topping for a sort of cottage pie