Place a large pan over medium-low heat and pour in –3-4 Tbsp of EVOO.
Add the chopped onion and sauté until golden brown, stirring frequently. If the onions start to stick or burn, add a splash of water and continue cooking.
Stir in the parsley, a touch more EVOO if needed, and keep stirring to combine. Then, bring 1 litre of water to a boil in a large pot. Add 1 tablespoon of salt and mix to dissolve, then add the pasta and give it a quick stir to prevent sticking. For cooking time refer to the instructions on your packet.
While the pasta is cooking zest the lemon directly over the pan, adding as much as you like. Squeeze the lemon juice into a small sieve to catch the seeds, then pour the juice into the pan and mix through.
Add the capers to the pan and season with a small pinch of salt. Crack black pepper over the mixture, adjusting the amount to your taste, and stir together.
Once the pasta is nearly ready, scoop out a mug of pasta water and set it aside. Drain the pasta using a colander, then transfer it directly to the pan with the sauce.
Add a splash of pasta water to the pan and toss the pasta to coat. If the mixture looks dry, add more pasta water gradually, tossing as you go.
Stir in the Philadelphia cream cheese, mixing thoroughly until it melts into the sauce. Add more pasta water if needed to achieve a creamy consistency and toss to ensure all ingredients are well incorporated.
Turn off the heat and gently stir in half of the salmon. Reserve the other half for garnish.
Give the pasta a final toss, adding more pasta water if it looks dry.