My mum's lasagne (adapted to be low carb) Serves 6-8
1 tbsp Coconut oil
4 shallots
1 carrot
1 leek
1 celery stick
4 garlic cloves, crushed/minced
800g mince ( "ordinary" - not steak mince)
1 cans tomatoes
1 carton passata
1 tbsp tomato purée
500 ml beef broth (can be made with 1 oxo cube)
2 teasp. salt
pepper
2-3 courgettes, thinly sliced on the diagonal
2 eggs (beaten)
500g cottage cheese or ricotta
Plenty of grated Parmesan
500g thinly sliced mozzarella
Dried basil & oregano
Blitz the veg in a good processor (the selection of veg, with the exception of the shallots, is optional - whatever you have in your fridge). Soften in a large saucepan with the coconut oil and salt. Meanwhile, roast the mince off in the oven (40 minutes at 180C, stirring and breaking up periodically this is an adaption acquired from Tom Kerridge's book ).
Add the mince to the veg, together with the canned tomatoes, passata, paste and beef broth. Season and leave to simmer for c2 hours to make a lovely rich ragu sauce. (This also makes an excellent base for bolognaise).
Mix the eggs with the cottage cheese (I've found it makes no difference if you use the more expensive ricotta).
Spoon a layer of the ragu sauce in a large shallow dish. Layer courgettes, all the cheeses, ragu sauce, herbs. Repeat layers until all ingredients used, finishing with a layer of ragu, mozzarella and Parmesan. Bake at 190C (170C fan) for 30 minutes. Or freeze unbaked, wrapped in foil and then bake for 1 hour (maybe probably more or is just that I have a very good freezer? )
The main alteration I made was substituting lasagne sheets for courgettes. You can also make it half with lasagne sheets (for stroppy, pasta loving teenagers like ds 
) and half with courgettes. In which case I soak the lasagne sheets briefly in boiling water to soften them.
It is very more-ish (supposedly serves 8-10 but mine usually only stretches to 6 
)