In a bowl, combine flour, garlic salt and Herbes de Provence; whisk well. Transfer half of the flour mixture to a re-sealable plastic bag and add half of the chicken thighs. Close the bag and shake until chicken is well coated. Shake each piece to remove any excess flour and place on a large plate. Add the remaining flour to the bag and coat the remaining chicken thighs.
In a large ovenproof saucepan over medium heat, add 3 tablespoons clarified butter. When hot, add thighs and cook 8 minutes per side or until brown; season with sea salt and freshly ground black pepper.
Drizzle Cognac over and warm it up for 2 seconds before flambéing it. Let it burn until it goes out on its own. Add shallots and pressed garlic, sauté all the ingredients for 1 minute. Add 1 cup red wine and cook until liquid reduces by half, deglazing the pan at the same time by scraping the bottom to dislodge any brown bits.
Make a bouquet garni by mixing thyme, rosemary, chervil, basil, celery seeds and freshly ground black pepper. Transfer the spices to a small sachet or a cheese cloth; tie up with kitchen twine.
When the wine has reduced by half, add Basic Brown Sauce, the bouquet garni and season with more sea salt and freshly ground black pepper. Stir well, making sure the sachet is submerged and cook for 15 minutes, stirring occasionally.
Transfer saucepan to a 350ºF preheated oven and cook for 15 minutes.
Using another saucepan over medium heat, add 1 tablespoons clarified butter. When hot, add pearl onions and sauté for 2 minutes, flipping often. To this add mushrooms and sprinkle with a little ground sea salt; crack some freshly ground black pepper and cook for 2 to 3 minutes. Pour in 2 tablespoons red wine and cook until the liquid has completely evaporated, about 2 more minutes.
Remove the saucepan from the oven and add the onion/mushroom mixture. Stir well, cover and return the saucepan back to the oven; cook for an additional 15 minutes.
When time is up, remove from the oven and using tongs, remove sachet of bouquet garni and discard. Sprinkle with fresh chopped parsley. 4 servings.
