Season chicken thighs generously with salt and pepper on both sides. Heat a large skillet over medium-high heat and add butter.

Once butter is melted and foaming, add chicken thighs skin-side down. Cook for 5-7 minutes until skin is golden brown and crispy. Flip and cook another 3-4 minutes on the other side. Remove chicken and set aside.

In the same skillet, add diced onions and cook for 3-4 minutes until softened. Add minced garlic and cook for another minute until fragrant.

Pour white wine into the skillet to deglaze, scraping up all the browned bits from the bottom of the pan. Let wine simmer for 2-3 minutes to reduce slightly.

Transfer the wine mixture to your slow cooker. Add chicken broth, thyme, rosemary, and bay leaves. Stir to combine.

Add halved potatoes, carrot rounds, quartered mushrooms, and chopped celery to the slow cooker, distributing them evenly.

Place the browned chicken thighs on top of the vegetables, skin side up. Pour any accumulated juices from the resting chicken into the slow cooker.

Cover and cook on LOW for 6-7 hours or HIGH for 3-4 hours, until chicken is tender and vegetables are cooked through.

About 30 minutes before serving, whisk together flour and heavy cream in a small bowl until smooth and no lumps remain.

Carefully remove chicken from slow cooker and set aside on a plate. Stir the cream mixture into the stew, mixing thoroughly to distribute evenly.

Return chicken to the slow cooker, cover, and cook on HIGH for an additional 20-30 minutes until sauce has thickened to desired consistency.

Remove bay leaves before serving. Taste and adjust seasoning with additional salt and pepper if needed. Garnish with fresh chopped parsley.