Fettuccine Alfredo with Asparagus

A drop of vodka enhances the taste, adding a little sharpness to the creamy sauce.
Prepare the pasta according to the instructions on the package. Drain in a colander over a bowl. Save 1/4 cup of water for the pasta.Preheat a large skillet over medium-high heat. Pour the oil into the pan; stir to coat. Add the asparagus, 1/4 teaspoon salt and 1/4 teaspoon pepper; simmer for 6 minutes or until soft and crisp. Remove from heat. Add the zest and juice; toss to combine. Keep warm.Melt the butter in a medium saucepan over medium-high heat. Add vodka and garlic; cook for 1 minute. Add the cream cheese, stirring until smooth. Add the milk, parmesan cheese, remaining 1/2 teaspoon salt and 1/4 teaspoon pepper. Add the remaining pasta water, pasta, and asparagus; stir to coat the noodles. Sprinkle with green onions.