- Cook your pasta in a pot of well salted boiling water until al dente, in a creamy sauce you don't want it in there too long so undercook it by a minute. Reserve some pasta water before draining. 
- When cooking time is getting close start your sauce. 
- Squeeze as much water out of the frozen spinach and set aside. 
- Heat the butter over a medium heat in a large frypan and when foamy and melted add the fresh herbs and garlic, cooking gently for 1 - 2 minutes (try and time this so you can get the cream in before anything is catching or browning in the pan) 
- Add the cream and whisk well gently scraping anything off the bottom. 
- Lower the heat slightly if needed and add the lemon juice, letting it seperate and then come back to an emulsion by whisking for 30 seconds or so. 
- Add the parmesan in a few additions, whisking until it has just melted and incorporated. 
- Add your cooked pasta straight in and mix. 
- Add ¼ cup of pasta water and let it all gently bubble away for a few minutes, just at a slightest of simmers, never boiling. 
- This sauce will never thicken much so you want to see it bubble to know it is doing something. 
- When most of the pasta water has cooked off add another ¼ cup, add the spinach and sausages and cook for another couple of minutes. 
- If you've undercooked your pasta right it should be a perfect consistency by the time it has been bubbling away in the sauce for 4 - 5 minutes. 
- Season with a few big cracks of black pepper to taste and lots of parmesan on top!