Preheat oven to 425℉.

Zest lemons. Cut 1 into thin wedges and juice the other. Set lemon juice & slices aside. Mince garlic and rosemary. Mix together zest, rosemary and garlic- set aside.

Peel and slice onions. In a large baking or roasting pan layer onion and lemon slices.

Place chicken on cutting board breast side down. With a sharp pair of kitchen shears cut along one side of back bone and then along other side to completely remove spine. Turn chicken over and press down on breast meat until you hear a crack. Tuck wings tips under body of chicken.

Place chicken on top of lemon and onion slices, breast side up. Carefully loosen skin from meat. Gently place rosemary, garlic, zest mixture in between skin and meat making sure to cover as much of the chicken as possible.

Drizzle olive oil over the top of chicken and message into skin. Salt and pepper.

Bake in a 425℉ oven for approximately 25-30 mins. Halfway through baking add lemon juice to the bottom of the roasting pan and continue baking.

Cooking time is an approximation and meat should reach an internal temperature of 165℉ using a meat thermometer.