In large saucepan, melt butter and saute mushrooms over medium heat for 3 minutes. Reduce heat to low. Add half & half and white pepper. Steam shrimp and add to sauce. Cook sauce over low heat for 15-20 minutes, stirring often.
Steam asparagus until tender-crisp, 5-8 minutes. Do NOT add to sauce. Stir cornstarch into 1/2 cup COLD water. Gradually stir into sauce until it thickens, about 5 minutes. Cook pasta and drain per directions.
Put asparagus on serving of pasta, cover with sauce, serve immediately. Sprinkle with Parmesan cheese, if desired. Serves 6 easily.
