Step 1

Cook your pasta in a large pot of well salted water according to package instructions (I undercook dried pasta by a minute so it can bubble away in the sauce at the end and not overcook).

Step 2

In a large skillet melt 1 tablespoon of butter over medium heat and gently fry the onions for 5 - 6 minutes, adding a pinch of salt half way through. Cook until soft and glassy. You don't want lots of colour on them so lower the heat if you need and keep moving round.

Step 3

Set them aside on a plate.

Step 4

Melt the remaining 1 tablespoon of butter over a medium-high heat and when sizzling add the sausage meat. Break up with a wooden spoon but don't move around too much as you want some nice colour on it.

Step 5

Cook for 3 - 4 minutes until cooked through.

Step 6

Add the sage and fennel seeds if using and cook for a 30 seconds - 1 minute.

Step 7

Lower the heat, push the meat to one side of the pan and add the cream, you only want a very gentle simmer, it shouldn't ever be boiling. (see video below!)

Step 8

Don't worry if the cream looks a bit dodgy with the butter and sausage fat at top, it will come together once you whisk the cheese in.

Step 9

Add the parmesan to the cream, in a two seperate lots, letting it melt into the cream before adding the next lot. I like to use a whisk.

Step 10

Add the black pepper and lemon juice and mix quickly with a whisk.

Step 11

Add your cooked pasta straight into the sauce along with the onions, toss well and let it all bubble away gently for a minute or two.

Step 12

Taste for seasoning and add a pinch or two of sea salt if it needs it.

Step 13

Add a splash of pasta water to loosen if you need.

Step 14

Serve with extra parmesan and lemon zest on top.