Wild Mushroom Risotto

Name: Wild Mushroom Risotto
Ingredients: 9 1/2 tablespoons butter, divided; 1 1/2 pounds fresh wild mushrooms (such as cèpe [porcini], hen of the woods, chanterelle, or stemmed shiitake); large mushrooms sliced, small mushrooms halved or quartered; 7 cups (about) low-salt chicken broth; 1 tablespoon extra-virgin olive oil; 3/4 cup finely chopped leek (white and pale green parts only); 1 1/4 cups arborio rice (8 to 9 ounces); 1/4 cup dry white wine; 1/4 cup dry white vermouth; 1/4 cup grated Parmesan cheese plus additional for serving (optional)