Wild Mushroom Risotto

Melt 2 tablespoons butter in heavy large skillet over medium-high heat. Add 1/4 of mushrooms and sprinkle with salt. Sauté mushrooms until tender and beginning to brown, 3 to 4 minutes. Transfer mushrooms to medium bowl. Working in 3 more batches, repeat with 6 tablespoons butter, remaining mushrooms, and salt and pepper.

Bring 7 cups chicken broth to simmer in medium saucepan; keep warm. Melt remaining 1 1/2 tablespoons butter with olive oil in heavy large saucepan over medium-low heat. Add leek, sprinkle with salt, and sauté until tender, 4 to 5 minutes. Add rice and increase heat to medium. Stir until edges of rice begin to look translucent, 3 to 4 minutes. Add white wine and vermouth and stir until liquid is absorbed, about 1 minute. Add 3/4 cup warm chicken broth; stir until almost all broth is absorbed, about 1 minute. Continue adding broth by 3/4 cupfuls, stirring until almost all broth is absorbed before adding more, until rice is halfway cooked, about 10 minutes. Stir in sautéed mushrooms. Continue adding broth by 3/4 cupfuls, stirring until almost all broth is absorbed before adding more, until rice is tender but still firm to bite and risotto is creamy, about 10 minutes. Stir in 1/4 cup grated Parmesan cheese, if using. Transfer risotto to serving bowl. Pass additional Parmesan cheese alongside, if desired.