Pre heat the oven to 190C.
Cut the sweet potato roughly into inch cubes. Season with salt and pepper and pour over 1 tbsp of melted oil, massage well so the potato is evenly cover in oil and roast in the oven for 40 minutes until cooked through and golden.
While this is cooking make the tomato sauce. Finely chop the onion and sauté in 1 tbsp of oil for 5 minutes until soft. Crush the garlic cloves and add them in, stirring for 30 seconds then pour in the can of tomatoes and let this cook to a simmer for 30 minutes, uncovered.
To make the spinach, heat ½ tbsp. of oil in a large pan and slowly add the spinach until it is all in the pan. Keep stirring so it wilts down, then throw in the nutmeg and a pinch of salt and stir again. Place into a colander and drip dry.
To make the bean mixture blend the beans with the zest of ¼ of a lemon and the juice of that same quarter and a tbsp of oil. Take two tbsp of this and mix it with the yogurt. (this will be left for the very top layer)
Peel the courgettes and parsnips lengthways so you get lots of lovely thin strips. Boil the parsnip for 3-4 minutes until tender but not totally cooked through.
Once the sweet potato is ready take it out and mash it roughly with a fork.
Turn the oven up to 200C.
Right, lets get stacking! Grab a nice pie dish that can hold about 800g to stack the ingredients up.
Take about 1/3 of the veggie strip and place down on the bottom of the dish
Then a nice layer of tomato, again this should be about 1/3 of the mixture.
Followed by roasted sweet potato, again about 1/3 of the mixture.
Add another 1/3 of Spinach
Add another layer of Bean Bechamel again about 1/3
Repeat again until everything is finished up (about 3 layers)
Top with the yogurt mixture, salt and pepper
Place in the oven and roast for 25-30 minutes until bubbling and golden on the top.
Images: Holly Clark Photography