Pat the chicken breasts dry with paper towels, then season generously with salt and pepper on both sides. Heat a large skillet over medium-high heat, adding a tablespoon of butter or oil. Once shimmering, carefully place the chicken breasts in the pan and sear for 6-7 minutes until golden and crispy on the bottom.
Flip the chicken and cook for another 5-6 minutes, or until the internal temperature reaches 75°C/165°F. Remove the cooked chicken from the skillet and let it rest on a plate for 5 minutes, which helps keep it juicy.
In the same skillet, add a bit more butter if needed, then toss in the sliced mushrooms. Cook for 5-7 minutes, stirring occasionally, until they release moisture and turn a deep golden brown with slightly crispy edges. The aroma of earthy mushrooms will fill the kitchen.
Add the minced garlic to the mushrooms and cook for about 30 seconds, stirring constantly until fragrant. Be careful not to burn the garlic, as it can turn bitter and overpower the sauce.
Pour in the heavy cream, scraping up any browned bits from the bottom of the skillet with a wooden spoon. Stir in the thyme leaves, then bring the mixture to a gentle simmer. Let it cook for 3-4 minutes until the sauce thickens slightly and develops a rich aroma.
Slice the rested chicken into thick strips and add them back into the skillet, nestling into the creamy mushroom sauce. Let everything simmer together for another 2 minutes, allowing the flavors to meld and the chicken to reheat.
Check the sauce's consistency; it should coat the back of a spoon with a velvety finish. If it’s too thin, simmer for a few more minutes. If it’s too thick, stir in a splash of chicken broth or water to loosen it up.
Taste and adjust the seasoning with more salt and pepper if needed. For an extra touch of freshness, squeeze a little lemon juice over the dish just before serving. Serve hot, spooning the creamy mushroom sauce over the sliced chicken and mushrooms.
