Set a 10-inch, straight-sided saute pan over medium-high heat and add the oil. Season the chicken thighs with the Essence, salt and pepper.
Place the chicken, skin side down in the pan and sear until golden brown, about 3 to 4 minutes. Turn the chicken over and sear on the second side for another 3 to 4 minutes. Remove the chicken from the pan and add the butter and mushrooms. Saute the mushrooms, stirring occasionally, until browned and most of the liquid has evaporated, about 4 to 5 minutes.
Add the onions and garlic to the pan and saute for 3 to 4 minutes. Sprinkle the flour into the pan and cook, stirring often to make a light brown roux, about 4 to 5 minutes.
Add the tomato paste, stock and rosemary to the pan, bring to a boil and reduce to a simmer.
Return the chicken to the pan, skin side down and cook the chicken for 30 minutes. Turn the chicken over and cook until the meat is very tender, about 30 minutes.
Serve the chicken over rice and garnish with the chopped parsley.
Emeril's ESSENCE Creole Seasoning (also referred to as Bayou Blast): Combine all ingredients thoroughly.