Cook the pasta in a large pot of salted boiling water according to package instructions. Drain.
While the pasta boils, prepare the sauce. Toss the salmon in flour.
Melt butter in a large skillet or Dutch oven over medium-high heat. Add salmon and saute for 1 minute. Add garlic, onion, mushrooms, salt and pepper. Cook until garlic is golden and mushrooms are tender, about 5 minutes. Stir in white wine, scraping the browned bits from the bottom of the skillet as you stir.
Reduce the heat to medium-low and simmer until the sauce is reduced by half. Add cream and reduce to a medium consistency. Stir in frozen peas and cook for 1-2 more minutes, or until heated through. Remove from heat.
Add cooked pasta to the skillet and toss to coat. Taste and season with additional salt and pepper, if necessary. Garnish with fresh parsley and serve.
Notes
Toss the salmon with flour before cooking. This serves two purposes: it helps to get a nice crust and sear on the outside of the fish, and it also helps to thicken the cream sauce.
Start cooking the sauce once the pasta water is boiling, because it comes together very quickly in the skillet.
Use a good quality white wine that you would actually like to drink. A crisp, dry white wine is ideal, so look for Pinot Grigio, Sauvignon Blanc, Pinto Gris or even Chardonnay.
Let the cream come to room temperature before adding it to the hot skillet.
For a spicy kick, add crushed red pepper flakes to the sauce.
Garnish the pasta with plenty of freshly-grated Parmesan and as many fresh herbs as you like!