Pat the chicken breasts dry with paper towels, then season generously with salt and pepper on both sides. Preheat your cast iron skillet over medium-high heat until hot and shimmering.
Add a tablespoon of oil to the hot skillet. Carefully place the chicken breasts skin-side down, pressing them lightly to ensure contact. Sear for about 5-7 minutes, until the skin is golden and crispy, with a satisfying crackle.
Flip the chicken carefully using tongs and reduce the heat to medium. Continue cooking for another 8-10 minutes, until the internal temperature reaches 75°C (165°F). The chicken should be cooked through but still juicy.
While the chicken finishes cooking, slice the mushrooms thinly. Push the chicken to one side of the pan, then add the sliced mushrooms to the empty space. Sauté for 3-4 minutes until they turn golden brown and fragrant.
Remove the mushrooms and chicken from the skillet. Cover the chicken loosely with foil and let it rest for 5 minutes to lock in juices.
Add a tablespoon of butter to the skillet, then pour in the white wine (if using), scraping up any browned bits from the bottom. Let it simmer for 2 minutes until slightly reduced and fragrant.
Stir in the heavy cream and minced garlic. Cook over low heat for 2-3 minutes, stirring gently, until the sauce thickens slightly and becomes silky.
Return the mushrooms and chicken to the pan, spooning sauce over the top. Warm through for another 1-2 minutes, tasting and adjusting seasoning with salt, pepper, and a squeeze of lemon juice.
Transfer the chicken to serving plates, spooning additional sauce and mushrooms over each piece. Garnish with a sprinkle of fresh herbs if desired. Serve immediately, enjoying the crispy skin and luscious sauce.
