12 ounces spaghetti
- 4 tablespoons butter, divided
- 2 tablespoons extra-virgin olive oil
- 1/2 cup thinly sliced shallots (about 4)
- 1 pound fresh shiitake mushrooms, stemmed, sliced
- 6 tablespoons fresh lemon juice
- 1 3/4 cups vegetable broth
- 1 tablespoon grated lemon peel
- 1 pound asparagus, tough ends trimmed, cut crosswise in thirds
- 1/4 cup chopped fresh chives
4 ounces shaved Asiago cheese*
Cook spaghetti in large pot of boiling salted water until tender but still firm to bite, stirring occasionally. Drain.
Transfer pasta to large wide bowl.
Meanwhile, melt 2 tablespoons butter with oil in heavy large skillet over medium heat. Add shallots; sauté 1 minute. Add shiitake mushrooms; sprinkle with salt and pepper. Sauté shiitake mixture until soft, about 6 minutes.
Add lemon juice; cook 1 minute.
Add broth and lemon peel. Bring to boil, then reduce to medium and simmer until liquid is reduced by half, about 6 minutes. Add asparagus to mushroom mixture; simmer until asparagus turns bright green, about 2 minutes. Add chives and remaining 2 tablespoons butter and stir until butter melts. Season sauce to taste with the salt and pepper.
Pour sauce over pasta; toss to coat. Top with shaved Asiago and serve.