Cook the SeaPak Morey's Lemon Herb Salmon according to package directions while you make the pasta.
Bring a large pot of well-salted water to a boil. Add the pappardelle and cook to al dente per package directions.
In the last 3 minutes of cooking, add the asparagus. In the final minute, drop in the peas. Reserve 1 cup of pasta water, then drain everything together.
Meanwhile, in a large skillet over medium heat, melt the butter. Add the garlic and cook just until fragrant, about 30 seconds. Pour in the heavy cream and let it come to a gentle simmer.
Whisk in the Parmesan, lemon zest, and 2 Tbsp of the lemon juice. Taste and add the additional 1 Tbsp lemon juice if you'd like it brighter. Season with salt, pepper, and red pepper flakes if using.
Add the drained pasta, asparagus, and peas to the skillet, tossing to coat. Splash in pasta water a few tablespoons at a time until the sauce loosely clings to every strand.
Stir in the fresh dill. Flake the salmon into large pieces and gently lay them over the top of the pasta.
Serve immediately with extra Parmesan, more dill, and a final squeeze of lemon.