In a large pot of salted boiling water, cook the fettuccine 2 minute less than the recommended package cook time for al dente pasta. Reserve 1 cup pasta cooking water before draining.
In a food processor or blender, combine the milk, cottage cheese, sun-dried tomatoes, parmesan garlic, red pepper flakes, salt and pepper. Blend for 1-2 minutes until completely smooth.
Warm the sauce in a large skillet or sauté pan over low heat. You should gently reheat it. Do not let it bubble or simmer. Stir in 1/2 cup of the reserved cooking water.
Add the pasta, stirring it into the sauce. If the sauce need to thinned out to coat the pasta, add more cooking water, 2 tablespoons at a time.
Fold in the baby spinach, walnuts and parsley.
Divide the pasta onto serving plates or into bowls and garnish with grated parmesan and chopped walnuts.