How to Make It
Rinse porcini thoroughly. Combine porcini and 2/3 cup boiling water in a bowl; cover and let stand 30 minutes. Drain in a sieve over a bowl, reserving 1/4 cup soaking liquid. Chop porcini.
Cook pasta with 1 tablespoon salt in boiling water 10 minutes or until al dente; drain in a colander over a bowl, reserving 1/4 cup cooking liquid.
Heat oil in a large skillet over medium-high heat. Add shallots, mushroom blend, and garlic; sauté 5 minutes, stirring frequently. Stir in porcini, sherry, and 1/4 teaspoon salt; cook 1 minute or until liquid evaporates.
Finely grate 1 ounce cheese; crumble remaining cheese. Reduce heat to medium. Stir in pasta, 1/4 cup reserved cooking liquid, 1/4 cup reserved porcini soaking liquid, 1/4 cup grated cheese, cream, chopped sage, and pepper; toss well to combine. Drizzle with oil; toss. Place about 1 1/4 cups pasta mixture on each of 4 plates; top each serving with about 1 tablespoon crumbled cheese. Garnish with sage sprigs, if desired.