Season the chicken generously with salt and pepper. In a large fry pan over medium-high heat, melt the butter. Add the chicken and cook, turning once or twice, until golden brown on both sides, about 8 minutes total. Transfer the chicken to a plate.
Add the onions and sauté until barely softened, about 3 minutes. Add the mushrooms and sauté until their juices are released, about 5 minutes. Add the garlic and cook for 2 minutes more. Add the chicken broth and heavy cream.
Return the chicken and any juices from the plate to the pan and spoon the mushrooms over the chicken. Cover, reduce the heat to medium-low and braise the chicken until opaque throughout, 20 to 25 minutes. Stir in the thyme, parsley, cumin and season with salt and pepper.