1. Prepare the Broth

• Cut celery, carrots (into three segments), and skin-on onion (into 4 pieces). Roughly chop parsley. Set aside.
• Place a pot or Dutch oven on the stovetop at medium heat. Add oil and allow it to heat.
• Add celery, carrots, skin-on onion, rosemary sprigs, green onion (optional), and parsley to the pot or Dutch oven. Sauté for 3-5 minutes.
• Place the carcass into the pot or Dutch oven.
• Fill the pot 3/4 full with water.
• Add salt and ground pepper to the pot or Dutch oven. Increase the stovetop to high heat.
• When the broth begins to boil, cover the pot with its lid, lower the temperature of the stovetop to low heat and cook for 4 hours.
• For the last hour, raise the stovetop to medium heat and remove the lid to reduce the broth.
• Strain broth through a fine seive and set aside. When you add the broth to the risotto, it should be warm.

2. Make Gremolata

• Finely chop flat-leaf parsley and mince garlic. Juice and zest lemon. Set aside.
• Combine flat-leaf parsley, garlic, lemon juice, lemon zest, extra virgin olive oil, salt, and ground pepper in a mixing bowl.

3. For the Risotto

a. Prepare Vegetables and Cheese

• Wash, dry, and thinly slice mushrooms. Peel and mince the shallots. Set aside.
• Grate Parmesan cheese. Set aside.

b. Sauté the Mushrooms in a Separate Pan

• Place sauté pan on the stovetop at medium heat.
• Pour 1 and 1/2 tablespoons of olive oil into a sauté pan, and sprinkle in mushrooms.
• Sauté for 5-7 minutes or until tender.
• Season with salt and ground pepper.
• Remove from heat and set aside.

c. Sauté Shallots

• Place a separate sauté pan on the stovetop at medium heat.
• Pour 2 tablespoons of olive oil into the pan and sprinkle in shallots.
• Sauté for 3 minutes or until translucent.

d. Stir Rice with Oil until Golden, then Add Wine and Broth

• Add rice. Stir, coating the rice with the oil.
• Sauté for 3 minutes or until the rice develops a light golden color.
• Add white wine. Lower the stovetop to medium-low heat to a slow simmer.
• When the wine is about 75% absorbed into the rice, add 1/2 cup of lamb broth. Stir occasionally and monitor closely.

e. Cook Slowly and Periodically Add Broth

• When the rice has absorbed 75% of the liquid, add another 1/2 cup of lamb broth.
• Stir with a spoon or toss rice occasionally, without using a spoon, in the pan.
• Repeat these steps until all 5 cups of lamb broth are added. This process should take 30 minutes.
• When the rice is al dente, remove it from the heat.

f. Stir in Mushrooms, Peas, and Cheese

• Stir in cooked mushrooms, frozen peas, Parmesan cheese, thyme leaves, and lemon juice.

g. Let's Plate

• Garnish with gremolata.
• Serve and enjoy!