Place a large pot over a medium heat and add the butter. Allow it to melt before adding the cracked pepper, letting it cook and bloom for a minute or two. Once it is fragrant, add the stock and bring to a simmer.
Add the pasta and stir well to separate the pieces from each other. Cook until it is al dente – this timing will vary for different gluten free brands, so keep your eyes on it. The pasta will soften in the liquid, so it’s important not to overcook it.
While the pasta is cooking, place the basil, spinach, lemon juice and pasta water (just scoop it straight out, making sure not to take any pastinto your food processor. Allow the pasta water to cool a little, particularly if you are using a Nutribullet. Once it has, blend to combine into a super smooth sauce. Add the freshly grated pecorino and repeat until smooth. Set aside.
Once the pasta is al dente, take it off the heat and add the peas, or whatever veg you fancy. If you’re using a firm veg you will need to add it a little earlier or cook it separately.
Pour the pesto sauce into the pasta and stir to combine. Make sure the stock isn’t boiling or it might brown the colour of the pesto. Serve immediately, with some extra pepper, basil and optional cream on top.
Best eaten within a day or so, as the pasta absorbs a lot of the stock over time and starts to fall apart.