1 pound trimmed asparagus spears, fresh or frozen
salt and pepper
8 ounces sliced mushrooms
2 tablespoons butter
1/4 cup all-purpose flour
1 1/4 cup milk
2 teaspoons lemon juice
2 tablespoons grated Parmesan cheese
Heat warming drawer or preheat oven to 225°. Put asparagus in a pan large enough to hold them lying flat. Pour enough boiling water in the pan to cover asparagus; add salt, to taste. Cover and simmer gently for 10 to 15 minutes, or until tender.
Lift asparagus out carefully with a spatula; transfer to paper towels to drain. Reserve 1/4 cup of cooking liquid. Arrange asparagus with tips all pointing in one direction on a warm, ovenproof serving dish; cover and keep warm in warming drawer or in a 225° degree oven. Simmer mushrooms in half of reserved asparagus liquid (2 tablespoons) for about 2 minutes, or until tender.
Drain and arrange over the bottom half of asparagus, leaving tips uncovered. Cover and continue to keep warm while making sauce.
In a small saucepan over low heat, melt butter; stir in flour until smooth. Continue to cook and stir for 1 to 2 minutes, until golden in color. Remove from heat; gradually stir in milk, the remaining half of asparagus cooking liquid (2 tablespoons), and lemon juice. Season with salt and pepper to taste. Return sauce to heat; simmer for 2
minutes, stirring constantly, until thickened. Pour over mushrooms and sprinkle
with Parmesan cheese. Asparagus tips will remain exposed. Cover exposed
asparagus with foil; place dish under broiler for 2 to 3 minutes, or until sauce
with cheese is browned.