Preheat oven to 450 degrees F.
Rub hens with 1 tablespoon of the olive oil. Lightly season hens with salt and pepper. Place 1 lemon wedge and 1 sprig rosemary in cavity of each hen. Arrange in a large, heavy roasting pan, and arrange garlic cloves around hens. Roast in preheated oven for 25 minutes.
Reduce oven temperature to 350 degrees F. In a mixing bowl, whisk together wine, chicken broth, and remaining 2 tablespoons of oil; pour over hens. Continue roasting about 25 minutes longer, or until hens are golden brown and juices run clear. Baste with pan juices every 10 minutes.
Transfer hens to a platter, pouring any cavity juices into the roasting pan. Tent hens with aluminum foil to keep warm. Transfer pan juices and garlic cloves to a medium saucepan and boil until liquids reduce to a sauce consistency, about 6 minutes. Cut hens in half lengthwise and arrange on plates. Spoon sauce and garlic around hens. Garnish with rosemary sprigs, and serve.