In a large bowl, place drumsticks and thighs; add Dijonnaise. Mix until chicken is well coated, cover and transfer to the refrigerator for 1 to 2 hours.
Preheat oven to 375ºF. In a large ovenproof saucepan over medium heat, add clarified butter. When hot, place thighs (skin side down) and drumsticks. Scoop Dijonnaise from the bowl and add to the pan; season chicken with freshly ground black pepper and sea salt. Cook 5 to 6 minutes per side or until golden brown. Transfer chicken to a bowl and set aside.
Return saucepan to the heat and add shallots with garlic; sauté for 1 minute. Add mustard seeds and sauté for 30 seconds before adding Herbes de Provence, lemon zest and white wine. Cook for another 30 seconds, scraping the bottom of the pan to loosen any browned bits. Pour in chicken broth and continue deglazing. When all browned bites are dislodged, add heavy cream and stir to combine. Return chicken to the saucepan and dip a sprig of rosemary in the sauce and baste chicken with it; leave sprig in the pan. Transfer to the preheated oven and cook for 30 minutes.
Half way through cooking, remove from the oven, pause timer and baste chicken generously. Return to the oven, restart the timer and cook for the remaining time or until internal temperature reads 165ºF. Baste again before serving.