Bring a large saucepan of salted water to the boil and blanch the kale for two to three minutes. Remove from the water with a slotted spoon and refresh immediately in a bowl of ice cold water. Repeat the process with the spinach, but reduce the cooking time to 30 seconds. It’s important you don’t overcook your leaves as not only will that destroy all their nutrients, you'll also lose their vibrant green colour.
Once all your leaves are blanched, squeeze out any water. Throw the spinach, kale, chilli and parsley into a food processor and whizz for a few seconds. Scrape out the green goodness into a bowl and add the oil, ricotta, 30g of the parmesan, the nutmeg, lemon zest, salt and pepper. Mix together until everything is well combined, and taste for seasoning. Transfer the mixture into a piping bag, squeezing the mixture towards the nozzle so it is nicely compacted and ready to pipe. This might seem a bit cheffy, but it makes life so much easier.
When you’re ready to assemble the bake, preheat the oven to 220°C. Bring a large pan of salted water to the boil, and cook your pasta shells for ten minutes. Don’t fully cook the pasta – the shells should retain a good amount of bite (a little more than the standard ‘al dente’), as the remaining cooking will be done in the oven. Drain and allow to cool until you can handle them.
To fill the pasta, cup a shell in one hand with the piping bag in the other, and with your thumb open up the shell and squeeze about a tablespoon of filling into the cavity. Repeat until all the pasta and filling is used up.
Take a medium size ceramic baking dish (about 26cm square) and pour in the tomato sauce. Then arrange the filled pasta shells on top, packing them in tightly and pressing them down a little into the sauce. Tear the mozzarella and scatter over the top, followed by the remaining parmesan. Bake in the hot oven for 20 minutes until the cheese is delicious and bubbling and serve with a simple green salad.