Roasted Chicken Thighs with Fennel and Orange

Name: Roasted Chicken Thighs with Fennel and Orange
Ingredients: 4 thigh with skin chicken thighs (about 1 1/2 pounds); 2 bulbs fennel (each about the size of your fist); 3 tablespoons olive oil , divided; 2 teaspoons kosher salt , divided; 1/2 teaspoon freshly ground black pepper , divided; 1 navel orange , scrubbed clean and sliced into quarter-inch rounds; 2 cloves garlic , grated with a microplane or finely minced; 2 teaspoons roughly chopped fresh thyme leaves, plus 6 whole sprigs (optional)