Step 1: Prepare the Chicken

Begin by preparing your chicken breasts. If they are particularly thick, you can butterfly them by slicing horizontally through the center to create two thinner cutlets from each breast. This will ensure they cook more evenly and quickly. Pat the chicken breasts dry with paper towels. This is a crucial step as it helps the chicken to brown properly when sautéing. Season the chicken breasts generously on both sides with salt and freshly ground black pepper. Don’t be shy with the seasoning – it’s the foundation of flavor for your chicken.

Step 2: Sauté the Chicken

Place a large skillet, preferably cast iron or stainless steel for even heat distribution, over medium-high heat. Add the olive oil and butter to the skillet. Allow the butter to melt completely and the oil to heat up until it shimmers slightly. This indicates the pan is hot enough for searing. Carefully place the seasoned chicken breasts in the hot skillet, ensuring not to overcrowd the pan. If necessary, cook in batches to maintain proper searing temperature. Sear the chicken for about 4-5 minutes per side, or until they are golden brown and cooked through. The internal temperature should reach 165°F (74°C). Once cooked, remove the chicken from the skillet and set aside on a plate, loosely tented with foil to keep warm while you prepare the sauce.

Step 3: Sauté the Aromatics

In the same skillet, reduce the heat to medium. Add the diced onion to the skillet and sauté for about 5-7 minutes, stirring occasionally, until it becomes softened and translucent. As the onion softens, it will release its natural sugars and develop a sweeter flavor, forming the base of your sauce. Next, add the minced garlic to the skillet and sauté for another 1-2 minutes until fragrant. Be careful not to burn the garlic, as it can turn bitter quickly. The aroma of sautéed garlic is a signal that it’s ready.

Step 4: Add Mushrooms and Cook

Add the sliced cremini mushrooms to the skillet with the onions and garlic. Increase the heat slightly to medium-high if needed. Sauté the mushrooms for about 8-10 minutes, stirring occasionally, until they release their moisture and begin to brown and soften. As the mushrooms cook, they will initially absorb the oil and then release their liquid. Continue cooking until this liquid evaporates and the mushrooms start to caramelize and develop a deeper, more intense flavor. Don’t rush this step, as properly cooked mushrooms are key to the dish’s flavor.

Step 5: Deglaze with White Wine (Optional)

If using white wine, now is the time to add it to the skillet. Pour the dry white wine into the skillet and increase the heat slightly to medium-high. Use a wooden spoon or spatula to scrape up any browned bits from the bottom of the pan. These browned bits, called fond, are packed with flavor and will enhance the sauce. Let the wine simmer for 2-3 minutes, allowing it to reduce slightly and the alcohol to evaporate. This process is called deglazing and it adds a wonderful layer of complexity and acidity to the sauce. If you are not using wine, simply skip this step and proceed directly to the next.

Step 6: Create the Creamy Sauce

Sprinkle the all-purpose flour over the mushroom mixture in the skillet. Cook for about 1 minute, stirring constantly, to cook out the raw flour taste and create a roux. This roux will help thicken the sauce. Gradually pour in the chicken broth, stirring continuously to prevent any lumps from forming. Continue stirring until the sauce begins to thicken slightly. Then, pour in the heavy cream and stir to combine everything well. Bring the sauce to a gentle simmer and allow it to cook for another 3-5 minutes, stirring occasionally, until it has thickened to your desired consistency. The sauce should be creamy and velvety, coating the back of a spoon.

Step 7: Add Thyme and Season

Stir in the fresh thyme sprigs (or dried thyme). Season the creamy mushroom sauce to taste with salt and freshly ground black pepper. Remember to taste and adjust the seasoning as needed, as the flavors will continue to develop as the sauce simmers. Remove the thyme sprigs if using fresh thyme before adding the chicken back.

Step 8: Combine Chicken and Sauce

Return the cooked chicken breasts to the skillet with the creamy mushroom sauce. Spoon the sauce over the chicken to coat it evenly. Let the chicken simmer in the sauce for a few minutes, about 2-3 minutes, to reheat through and allow the flavors to meld together. Ensure the chicken is heated through again before serving.

Step 9: Serve and Garnish

Remove the skillet from the heat. Sprinkle the freshly chopped parsley over the creamy mushroom chicken for garnish. Serve immediately while hot. This dish is fantastic served over rice, pasta, mashed potatoes, or alongside crusty bread for soaking up the delicious sauce.