Cavolo nero risotto

This recipe was developed for us by local chef, food writer, caterer and teacher, Alan Rosenthal. Find out more about him and his recipes on his website or follow him on Instagram.
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This risotto is vibrantly green. You could use an alternative green leaf here but I think cavolo gives the best colour and a lovely flavour to the dish.
Serves 2
Ingredients
40g butter
½ onion, finely chopped
200g cavolo stripped of thicker stalks and washed
2 cloves of garlic, grated
175g risotto rice
75ml dry white wine
600ml hot vegetable stock
75g Parmesan
Juice and zest of ½ lemon
Black pepper
Salt
To serve
More Parmesan
Extra virgin olive oil
method
Melt 30g of the butter in a small heavy based saucepan, over a medium heat (keep the rest of the butter in the fridge). Add the chopped onion and a pinch of salt and cook, stirring frequently, for 7 minutes until starting to soften.
Meanwhile, plunge your prepared cavolo nero into boiling salted water and cook for 3 to 4 minutes until very soft. Drain well and then blitz in a food processor until almost a purée.
Once the onions are ready, add the grated garlic and cook for a further 2 minutes.
Add the risotto rice and cook for 2 more minutes, stirring regularly to avoid it sticking. Now add the wine and allow it to reduce in the pan until nearly dry, continuing to stir.
Slowly add the vegetable stock, one ladle at a time, stirring regularly and not adding the next until the liquid has mostly been absorbed from the last ladle. Season generously with salt and black pepper and cook for around 18 minutes until the rice is al dente (it will take most of this time for all the stock to be added).
At around 16 minutes, add the puréed cavolo and allow to reheat and meld with the creamy rice. Once the rice is ready, turn off the heat, stir in the remainder of the butter, lemon zest and juice and the grated Parmesan.
Serve in bowls topped with a little more Parmesan, and a drizzle of extra virgin olive oil.