Bring a pot of water to a boil and add the pasta. Continue to boil until the pasta is tender, following package instructions. Drain and set aside.
Meanwhile, to a large skillet add the butter and garlic. Sauté the garlic over medium heat one to two minutes, or until soft but not brown. Reduce heat, add creme fraîche, 1 to 2 tablespoons of half and half to loosen it up, and the peas; gently simmer 2 to 3 minutes more. Add the salmon and dill; heat through and let the sauce thicken slightly.
Toss cooked pasta in the skillet with the sauce to coat. Season with salt and pepper to taste and top with shredded Parmesan. Stir gently to melt the cheese. Serve warm.