While your pasta is cooking to al dente, brown your sausage in a large pan, set aside.
In the same pan, add lemon zest. Add in heavy cream, whisk until simmering, add in butter slowly.
Mix in spinach and tomatoes, allow to cook down. Adjust seasonings, if needed.
Turn off heat, add in lemon juice, then your cooked pasta and cooked sausage, and a bit of reserved pasta water, if needed to thin sauce. Serve with grated parmesan and more lemon zest, if desired.