Rinse asparagus thoroughly. Break off tough bottoms. If thick peel stems. Blanch in boiling salted water until tender-crisp. Cut into 2-inch pieces. Melt 2 tablespoons butter in skillet. Saute lightly salted shrimp until cooked but still crisp. Drain and save the juice.
Melt 2 tablespoons butter in skillet. Add flour and whisk 3 minutes over heat until pale yellow. Add 2 cups heated cream. Bring sauce to a boil, whisking constantly. Season with pinch of nutmeg. Add asparagus and shrimp to sauce and heat, stirring constantly. Add salt and pepper to taste. If sauce becomes too thick, add enough shrimp liquid to reach desired consistency. Serve over lightly buttered noodles.