Cook pasta and hold Cook chicken breast and blanch asparagus; hold. Warm the butter in a large saucepan over medium-low heat. Add the onion and saute?until lightly brown and very soft. Add the flour and reduce the heat to low. Stir until completely blended. Very gradually whisk in the white wine and broth. Bring the sauce to a boil and then let simmer for 10 minutes. Stir in the lemon zest, thyme, dill, mustard and season to taste with salt and white pepper. Add the cooked and julienne chicken and asparagus. Serve over warm pasta with Parmesan cheese. Per serving: 675 Calories (kcal); 15g Total Fat; (21% calories from fat); 28g Protein; 93g Carbohydrate; 52mg Cholesterol; 470mg Sodium Food Exchanges: 6 Grain(Starch); 1 1/2 Lean Meat; 1/2 Vegetable; 0 Fruit; 1 1/2 Fat; 0 Other Carbohydrates Recipe by: Molly Walsh Converted by MM_Buster v2.0n.