Remove & discard the skins from the sausages then crumble the meat into small pieces.
Next, place a large pan over a medium heat then add in the olive oil & leave to heat up for a minute. Once the oil's hot, add in the crumbled up sausage meat then fry, stirring occasionally until it's well browned & caramelised. This will take 4-5 minutes.
Once the sausage meat is cooked, stir in the crushed fennel seeds then fry for another 30 seconds. Use a slotted spoon to transfer the meat to a bowl, leaving any fat/oil in the pan. Turn the heat down to medium-low.
Add the butter into the pan then once melted, add in the diced onion & a pinch of salt. Cook, stirring frequently until the onions are soft & translucent. This will take around 10 minutes.
Next, stir the grated garlic into the onions, cook for another 30 seconds then stir in the sausage meat. Turn the heat back up to medium.
Pour the white wine into the pan then cook, until reduced almost completely. Make sure to scrape the bottom of the pan with a wooden spoon, to deglaze the pan & release all the caramelised bits!
Whilst the pan is deglazing, bring a separate, large pan of salted water to the boil over a high heat. This is for cooking the gnocchi in.
Once the pan has been deglazed, add in the double cream, grated parmesan & lemon juice then stir to combine & season to taste with salt & pepper. Leave to simmer gently over a low heat whilst you cook the gnocchi.
Next, cook the gnocchi in the pan of water following the packet's instructions. You'll know when the gnocchi's cooked when it starts to float. This only tends to take around 3-4 minutes.