I eyeballed most of it but here's more or less what I did!! :)
Boiled some pasta (I used spaghetti, but I don't think it matters too much) and in the meantime prepared the sauce. If you like, you can keep some pasta water for the sauce.
For two servings of the sauce you will need:
2-3 handfuls of spinach (I used fresh spinach, but frozen should be fine)
One large clove of garlic
Double cream (about 75-100ml)
A small organic lemon* (for juice and also zest; you will have some juice left over - you can use that for example when roasting cauliflower or broccoli; the zest freezes beautifully :) )
Salt, pepper, a pinch of nutmeg
Clean and wash the spinach leaves, then dice the onion and crush the garlic clove. Zest the lemon, then squeeze it; take care to only get the actual peel, not the white stuff underneath as it will make the zest taste bitter.
In a pot or pan, roast the onion and garlic in olive oil on medium high heat for a couple of minutes, then add the washed spinach. Reduce the temperature to medium heat and let the ingredients cook until the spinach leaves have reduced their volume by about a half. (You can already put the salt in here.) Add the lemon juice TO TASTE - maybe about the volume of a shot glass? You can always add more later. (Optional: add a bit of pasta water.) Add a pinch of zest. Let it cook for 2-3 minutes - if you want to reduce some of the liquid, let it simmer for a few minutes longer - , then take the pot/pan from the heat and add the double cream. (The exact amount may vary due to the amount of spinach you put in.) Stir, then bring to a short boil. Add your spices: salt and pepper to taste, a sprinkle of nutmeg. Turn down the heat to zero and you're done :)
*you can also only use one half of the lemon (should be enough) and keep the other in the fridge: sprinkle some sugar on a saucer, then put the lemon half on it, cut side on the sugar, facing down. This helps keep it fresh and juicy :)