Heat a skillet over medium heat and add the olive oil. Sauté the onion for 3–4 minutes until it starts to soften, then add the garlic for about 30 seconds. This quick step builds flavor for the stew.

Add the chicken pieces to the skillet and lightly brown them on all sides. They don’t need to be cooked through at this stage—just a bit of color to deepen the flavor.

Transfer the browned chicken, onion, and garlic to your slow cooker. Add the sliced mushrooms on top.

Pour in the chicken broth and milk, then sprinkle in thyme, bay leaf, salt, and pepper. If you’re using flour for a thicker sauce, whisk it with a splash of the broth first to avoid clumps, then stir it into the slow cooker.

Cover and cook on low for 7–8 hours or on high for 3–4 hours, until the chicken is tender and the flavors have melded.

Taste and adjust seasoning. If the sauce needs a touch more thickness, remove the lid and allow it to simmer uncovered on high for 15–20 minutes, or mix a tiny amount of flour with a bit more broth and stir in until desired thickness is reached.

If you used milk, you’ll want to keep the heat gentle so it doesn’t curdle. A slow, steady simmer in the final minutes helps the sauce stay smooth.