Trim bottoms, then quarter Brussels sprouts. Add Brussels sprouts and 1 tbsp (2 tbsp) oil to a parchment-lined baking sheet. Season with pepper and half the garlic salt, then toss to coat. Roast in the middle of the oven until slightly softened, 5-6 min.
Meanwhile, zest lemon then cut half the lemon into wedges (all for 4 ppl). Roughly chop dill. Pat salmon dry with paper towels. Season with pepper and half the remaining garlic salt.
After 5-6 min, carefully remove Brussels sprouts from the oven. Stir, then push Brussels sprouts to one side. Transfer salmon, skin-side down, to the baking sheet, next to Brussels sprouts. Drizzle ½ tbsp (1 tbsp) oil over salmon, then sprinkle half the lemon zest over top. Roast in the middle of the oven until Brussels sprouts are golden-brown and tender and salmon is cooked through, 16-20 min.**
Meanwhile, heat a large non-stick pan over medium-high. Add linguine to the boiling water. Cook uncovered, stirring occasionally, until tender, 1-2 min. Reserve 1 ¼ cup (2 ½ cups) pasta water, then drain. When the pan is hot, add Cream Sauce Spice Blend and 1 tbsp (2 tbsp) butter. Cook, stirring occasionally, until butter melts and mixture is combined, 30 sec. Add cream cheese and 1 cup (2 cups) reserved pasta water to the pan. Bring to a simmer, stirring often, until mostly smooth.
When sauce comes to a simmer, add linguine, Parmesan and remaining lemon zest. Reduce heat to medium. Season with pepper to taste. Cook, stirring often, until cheese melts and sauce thickens and coats linguine, 1-2 min. (TIP: Add remaining reserved pasta water if sauce reduces too much.) Remove the pan from heat.
Add Brussels sprouts and 1 tsp (2 tsp) dill to the pan with linguine, then toss to combine. Divide linguine between plates, then top with salmon. Squeeze a lemon wedge and sprinkle any remaining dill over top, if desired.
If you've opted for jumbo salmon, season it in the same way the recipe instructs you to season the regular portion of salmon. To cook jumbo salmon, increase roast time to 16-20 min.