Adjust rack to top position and preheat oven to 425 degrees. Bring a large pot of heavily salted water to a boil. Wash and dry produce.

Cut broccoli into bite-size pieces. Finely crush crispy onions in their package (TIP: Once crushed, crispy onions should resemble breadcrumbs). Roughly chop half the Italian cheese blend. Zest and quarter lemon (for 4 servings, zest one lemon and quarter both).

Once water is boiling, add spaghetti to pot. Cook, stirring occasionally, 9-11 minutes.

Reserve 1½ cups pasta cooking water (2 cups for 4 servings), then drain. (Keep empty pot handy for making sauce.)

While pasta cooks, in a small bowl, combine crispy onions and chopped cheese.

Toss broccoli on one side of a lightly oiled baking sheet with a drizzle of oil, salt, and pepper. Roast on top rack for 10 minutes.

Pat salmon* dry with paper towels and season all over with half the garlic powder (you’ll use the rest in the next step), salt, and pepper. Once broccoli has roasted 10 minutes, remove sheet from oven. Carefully add salmon, skin sides down, to empty side of sheet. Evenly brush tops of salmon with Dijon and mound with crispy onion mixture, pressing lightly to adhere. (No need to coat the undersides.)

Return to top rack and roast until salmon is cooked through and crust is golden, and broccoli is browned and tender, 8-10 minutes.

Heat empty pot used for pasta over medium heat. Add 1 cup reserved pasta cooking water (1½ cups for 4 servings), cheese roux, and remaining garlic powder and whisk until combined. Cook, whisking, until slightly thickened, 2-3 minutes.

Reduce heat to medium low and whisk in cream cheese until melted and combined, 1 minute.

To pot with sauce, add drained spaghetti, roasted broccoli, garlic herb butter, half the lemon zest, remaining Italian cheese blend, 1 TBSP plain butter (2 TBSP for 4 servings), a big squeeze of lemon juice, and a pinch of chili flakes. Cook, stirring, until butter melts and pasta is coated in a creamy sauce, 1 minute. TIP: If needed, stir in more reserved pasta cooking water a splash at a time.

Taste and season with salt, pepper, and more lemon juice if desired.

Divide pasta between bowls. Top with salmon and sprinkle with remaining lemon zest and a pinch of chili flakes if desired. Serve with remaining lemon wedges on the side.