In a small saucepan, warm the chicken broth over medium-low heat. Keep it warm but not simmering.

In a large heavy-bottomed pan, heat 1 tablespoon butter and olive oil over medium heat. Add the shallot and leeks and half of the salt and pepper, cooking until softened, about 5 minutes. Stir in the garlic and cook for 30 seconds.

Add the risotto rice and stir for 1-2 minutes until the grains become slightly translucent around the edges.

Pour in the dry white wine and stir until mostly absorbed.

Add one ladle of warm broth at a time, stirring often. Once absorbed, add another ladle, repeating for about 20-25 minutes or until the rice is creamy and tender with a slight bite.

Stir in the cooked chicken, remaining salt and black pepper, and fresh thyme. Continue cooking for another 2-3 minutes, adding a splash more broth if needed.

Remove from heat and stir in the remaining 1 tablespoon butter, Parmesan cheese, lemon zest, and lemon juice. Adjust seasoning to taste.

Serve immediately, garnished with extra Parmesan and fresh thyme if desired.