In a medium bowl, place in the salmon and break into small pieces with a fork. Set aside.
Bring a large pot of water (salted) to a boil over high heat. Cook the pasta until tender but still firm to the bite, stirring occasionally. Save 1 cup pasta water. Drain pasta. Set aside.
Meanwhile, in a large skillet over medium heat, warm up the butter and olive oil. Add shallots and cook for 8 minutes. Throw in a dash of red pepper flakes. Add lemon juice and zest. Pour in the heavy cream and ½ cup reserved pasta water. Mix well. Cook until warm. Add the salmon pieces and cook for 2 minutes. Stir in the pasta. If the sauce is too thick, add a little more reserved pasta water. Season with salt and pepper. Serve immediately.