Chicken Thighs Braised with Creole Mustard

Name: Chicken Thighs Braised with Creole Mustard
Ingredients: 8 chicken thighs; 1¾ teaspoons fine sea salt, divided; 1 teaspoon freshly ground black pepper; 1 tablespoon extra-virgin olive oil; 3 celery stalks, trimmed and sliced on a bias into ¼-inch pieces, plus 1 tablespoon finely chopped celery leaves; 1 large yellow onion, halved and thinly sliced; 6 garlic cloves, thinly sliced; ¼ cup raisins; 1 bay leaf (preferably fresh); 1 rosemary sprig; 1 thyme sprig; 2 tablespoons creole or country-style whole-grain mustard; 1 cup dry white wine; 1 cup chicken broth; ½ cup heavy cream; 1 tablespoon finely chopped flat-leaf parsley leaves