How to Make It
Bring a large saucepan of salted water to a boil. Add the asparagus and cook until tender, 4 to 5 minutes. Drain and pat dry.
Melt the butter in a large skillet and cook until just beginning to brown. Add the mushrooms, season with salt and pepper and cook over moderately high heat, stirring often, until just tender, about 8 minutes. Add the shallots and thyme and cook, stirring, until softened, about 2 minutes longer. Add the asparagus and cook, tossing, until warmed through. Add the lemon juice, the chopped parsley and the whole parsley leaves and season with salt and pepper. Arrange on 4 plates and serve.