Total time: 50 minutes.
Preheat oven to 450º.
Drizzle oil in a small roasting pan or the bottom of a broiler pan. Place pan in oven 5 minutes or until oil is hot. Sprinkle chicken with 1/4 teaspoon salt and 1/4 teaspoon pepper. Place chicken, skin sides down, in pan. Arrange garlic, shallots, thyme sprigs, and fennel around chicken; sprinkle vegetables with 1/4 teaspoon salt and 1/8 teaspoon pepper. Bake at 450º for 20 minutes. Remove pan from oven. Turn chicken over; stir vegetables. Add plums to pan. Bake an additional 15 minutes or until chicken is done. Remove chicken and vegetable mixture from pan; discard thyme sprigs. Discard skin. Loosely cover chicken and vegetable mixture; keep warm.
Place pan over medium-high heat. Add 1/2 cup broth and wine, stirring to loosen browned bits. Combine flour and remaining 1/4 cup broth, stirring with a whisk until smooth. Add flour mixture to pan; stir until well blended. Bring to a boil; cook for 1 minute or until slightly thick. Stir in chopped thyme, remaining 1/4 teaspoon salt, and remaining 1/8 teaspoon pepper. Serve sauce with the chicken and vegetable mixture.