Preheat oven to 400°F.

Stir pesto and garlic in medium bowl to blend.

Spread 1 cup pesto mixture over outside and under the skin of chicken.

Place potatoes in large roasting pan and toss with remaining pesto mixture. Push potatoes to sides of pan; place chicken in center. Sprinkle chicken and potatoes with salt and pepper. Roast until thermometer inserted into thickest part of chicken thigh registers 180°F and potatoes are brown and tender, about 1 hour 20 minutes.

Transfer chicken and potatoes to platter.