Start by patting the chicken breasts dry and slicing them evenly into medallions or strips. Season lightly with salt and pepper.
Heat a large skillet over medium-high heat and add a tablespoon of oil. Once shimmering, place the chicken pieces in the pan, laying them flat. Sear for about 3–4 minutes per side until they turn golden brown and are cooked through. Transfer to a plate and cover loosely with foil.
In the same skillet, add a little more oil if needed. Toss in the sliced mushrooms and sauté for 5–6 minutes, stirring occasionally, until they release their moisture, turn deep golden, and smell earthy.
Add the minced garlic to the mushrooms and cook for about 30 seconds until fragrant—your kitchen will fill with a warm, pungent aroma.
Pour in the white wine, scraping up any browned bits from the bottom of the pan. Let it simmer and reduce by half, about 2–3 minutes, until the liquid has thickened slightly and smells fragrant.
Stir in the heavy cream, then squeeze in the lemon juice. Add chopped thyme or parsley if using. Reduce the heat to medium-low and let the sauce gently simmer for 3 minutes, allowing it to thicken and coat the mushrooms and chicken evenly.
Return the seared chicken to the skillet, nestling it into the sauce. Cook for another 2 minutes to rewarm and let the flavors meld. The sauce should look silky and cling to the chicken, while the chicken remains tender and juicy.
Turn off the heat, taste the sauce, and adjust seasoning with salt, pepper, or a squeeze more of lemon if desired. Let it rest for a minute, then serve hot, spooning the creamy mushroom sauce over the chicken for a comforting yet bright dish.
