Heat a medium-size nonstick saute pan. Remove from the heat and spray with vegetable oil spray. Add the onion and saute over medium heat unitl limp, about 5-10 minutes. Add the asparagus and the garlic, cover the pan, and turn off the heat. (The steam from the onion will cook the asparagus.)
In a large skillet, combine the dry milk and skim milk and whisk until blended. Add the flour, stir and cook over medium-high heat until thickened.
In a small bowl, add 2 tablespoon. of the hot sauce to the cream cheese and stir until smooth. Return this mixture to the hot sauce. Add the parmesan cheese and stir until melted. Keep hot. If the mixture becomes too thick, thin it out with small amounts of skim milk. The consistency should be like cream, not gravy.
Cook the fettuccine in boiling water according to the package directions until it is al dente and drain. Add the hot pasta and the garlic and the vegetables to the sauce in the skillet. Stir and cook over medium-Low heat until heated through. Serve garnished with the chopped arugula.