Preheat oven to 400 degrees F. Season chicken thighs generously with Lawry's seasoning salt, garlic powder, paprika, Sazon, and cracked black pepper. Let sit at room temperature for 15 minutes.

In a shallow dish, combine about 1/4 cup flour with any remaining seasoning. Coat each chicken thigh in the flour mixture, shaking off excess.

Heat 2 tablespoons oil in a large oven-safe skillet over medium-high heat. Once shimmering, place chicken thighs skin-side down and sear for 5 minutes until golden brown.

Carefully flip chicken thighs and brown the other side for 5 minutes. Remove chicken and set aside, leaving drippings in pan.

Reduce heat to medium. Add butter to the pan drippings. Once melted, add diced onion, minced garlic, and red pepper flakes. Saute for 3 to 5 minutes, stirring frequently, until onions become translucent.

Sprinkle in remaining flour (about 1/4 cup) and stir to form a roux, cooking for 1 minute until bubbly and lightly golden.

Gradually pour in chicken stock while whisking continuously to avoid lumps. Allow mixture to simmer gently, stirring frequently until thickened, about 4 to 6 minutes.

Stir in heavy cream until fully incorporated and gravy is smooth and velvety.

Return seared chicken thighs to the pan, nestling them into the gravy. Bring to a gentle boil, then cover skillet with lid or aluminum foil.

Transfer covered skillet to preheated oven and bake for 45 minutes until chicken reaches internal temperature of 165 degrees F and is tender.

Carefully uncover skillet and spoon gravy over chicken thighs. Garnish with fresh parsley and serve immediately.