The secret to the intense mushroom flavor in this recipe is that not only are mushrooms themselves part of the mix, but the risotto is cooked with mushroom-flavored broth. In order to use dried porcini mushrooms—or any dried mushrooms for that matter—you have to reconstitute them by allowing them to sit in hot water for a few minutes, absorbing that water and plumping up. Then the mushrooms are ready to cook with, and you have all this flavorful liquid as a byproduct. By all means, take advantage of it: Here, it works as a flavor booster to the chicken stock; but you can also use it as the base of a wonderful soup or sauce.
Bring the Broth to a simmer in a heavy, medium-size saucepan. Add the porcini mushrooms. Cover and set aside until the mushrooms are tender, about 5 minutes. Using a slotted spoon, remove the mushrooms and finely chop. Cover the broth and keep warm over very low heat.
Melt the butter in a large, heavy saucepan over medium heat. Add the onions and sauté until tender, about 8 minutes. Add the white mushrooms, porcini mushrooms, and garlic; sauté until the mushrooms are tender and the juices evaporate, about 10 minutes. Stir in the rice. Add the wine; cook, stirring often, until the liquid is absorbed, about 2 minutes. Add 1 cup of hot broth; simmer over medium-low heat, stirring often, until the liquid is absorbed, about 3 minutes. Continue to cook until the rice is just tender and the mixture is creamy, adding more broth by cupfuls and stirring often, about 28 minutes. Stir in the peas. Mix in the Parmesan cheese. Season with salt and pepper to taste.