Heat the oil in a large skillet over medium heat. Add the leeks and onion along with a pinch of salt and cook, stirring occasionally, until just tender, 6 to 8 minutes.
Stir in the garlic and rice cook for 2 minutes, stirring to make sure rice is coated in a little oil. Add the wine, lemon juice, and zest and season with salt and pepper (we add about 1/2 teaspoon each) and cook, stirring, until the wine is absorbed, about 2 minutes.
Add the broth and bring to a boil. Reduce heat to low and simmer, uncovered, until the liquid has absorbed and the rice is tender, 18 to 20 minutes. Remove from heat and stir in cream cheese, Parmesan and parsley. Set aside while you cook the fish.
Pat salmon dry and season only the skin-side with salt. Heat oil in a cast-iron pan over medium-high; add salmon, skin-side down and gently press each fillet with a spatula to ensure even contact with the pan. Cook until the skin is crispy, about 3 minutes. Season the flesh side with salt and pepper, then flip and cook a further 1-2 minutes. Transfer lemon rice to a serving platter (or dinner plates) and top with salmon. Garnish with lemon slices and parsley, if desired.