Cut the chicken into 6 serving pieces. Heat the oil in a large frying pan over high heat until sizzling hot. Season the chicken with salt and pepper; add to the pan, skin side down, and brown quickly. Then turn and brown the other side.
Reduce the heat to low, add the garlic cloves, and cook until soft but not colored, 5 to 8 minutes.
Add the sliced sage, season with salt and pepper, and stir in the wine. Bring to boil and then transfer to the oven.
Reduce the oven temperature to 375 and cook, uncovered, stirring occasionally, for 30 minutes. Then cover and cook the chicken until the juices run clear when thigh is pierced with the point of a knife, 15 to 20 minutes longer.
To serve, transfer the chicken pieces to a serving platter; cover with aluminum foil to keep warm. Strain the sauce through a fine sieve, pressing down on the solids to extract the garlic pulp; discard the solids.
Cook over medium heat until reduced by about one half. Spoon sauce over the chicken.