Despite the incredible simplicity of its ingredients, a true cacio e pepe takes a little practice in order to get right the almost alchemical blend of cheese and water to form that glossy, coating sauce. Though as it is so delicious, you won't mind how many times you practice making it!
Bring a shallow pan of water to the boil with plenty of salt. Add the pasta (the water should only just cover it) and simmer for 10 to 12 minutes until the pasta is tender, adding the kale 3 to 4 minutes before the end of the pasta cooking time.
At the same time, melt the butter in a large, high-sided frying pan, add the black peppercorns, then tip into a large bowl. Add the pecorino and mix together. Scoop out 250 milliliters (1 cup) of the pasta water while the pasta is still cooking and beat a little splash into the bowl to make a paste, then keep adding water gradually until you have a smooth sauce.
Drain the pasta and add it to the bowl of cheesy sauce along with the kale. Stir together, adding a little more pasta water until the whole thing is coated in a glorious glossy sauce. Serve immediately.
Make it veggie: swap the pecorino for a vegetarian alternative.