Bring a large pot of salted water to a boil. Cook the pasta until al dente, around 10-12 minutes, and reserve 1 cup of the pasta water before draining.

While the pasta cooks, dice the onions, mince the garlic, and grate the parmesan for readiness.

Pat the salmon chunks dry and season with salt and black pepper.

In a skillet, heat olive oil over medium-high heat and sauté the salmon for about 3-4 minutes on each side until golden. Remove and set aside.

In the same skillet, add diced onions and cook until translucent. Add butter, garlic, and dried parsley, stirring briefly.

Add half of the cooked salmon back to the skillet with red pepper flakes and stir.

Gradually pour in lukewarm milk, followed by reserved pasta water and parmesan, stirring until smooth.

Add cooked pasta to the skillet and toss gently, incorporating remaining salmon and warming through.

Finish with fresh lemon zest and additional parmesan. Serve immediately.