Bring a pot of salty water to the boil and cook your pasta until al dente.

While the pasta is cooking - get all your other ingredients ready and waiting: Grate the Parmesan cheese and measure out the creme fraiche. Beat the egg.

Drain the pasta over a bowl, reserving some of the cooking liquid.

Immediately put the pasta back into the pot it was cooking in, back on the stove and add a splash (about 1/4 cup) of the cooking liquid.

Add the spinach and stir it through the pasta, and put the lid on the pot and flash steam the leaves for a minute or two. Stir once or twice more to ensure the spinach is mixed into the pasta and is cooked. Turn off the heat.

Add the creme fraiche and lemon zest to the beaten egg and mix. Stir this through the very hot pasta and spinach to coat all the strands. The carry-over heat from the pasta will cook the egg. Add the Parmesan cheese and stir to fully to combine and then put the lid back on the pot for a minute or so to allow it all to integrate.

Check if it needs salt and pepper. It should be quite salty from the cheese and the pasta water.