Spray a small wire rack with non-stick oil and place in the bottom of the crockpot.

Rinse the chicken and pat dry with paper towels. Season the cavity with salt and pepper. Stuff the lemon quarters and all but 3 of the slices into the cavity. Add the sprigs of oregano, thyme and rosemary inside the chicken and tie the legs together with kitchen twine. Place the remaining 3 lemon slices on the bottom of the crockpot.

Place the chicken in the crockpot, breast side up on the rack. Brush olive oil over the top and sides of the chicken, season with additional salt and pepper. Sprinkle with the chopped oregano, thyme and rosemary. 

Put the lid securely on the crockpot and set the temperature to low and roast for 5 hours, or until internal temperature reaches 165°F with a meat thermometer.

Preheat oven to 500°F

Remove the chicken from the crockpot and transfer to a wire rack set over a rimmed baking sheet. Place in the center of the oven and watch closely for 5-8 minutes until the skin turns golden brown. 

Transfer to a cutting board, tent with foil and let rest for 10 minutes. Remove the lemon pieces and herbs from the cavity. Carve the chicken and place on a serving platter. Garnish with chopped parsley when ready to serve. 

While the chicken is resting, discard the lemon slices and pour the accumulated pan juice remaining in the crockpot through a fine-mesh strainer set over a small saucepan. There should be about 1 cup of liquid in the pan, if there is less, add some water or chicken broth to equal 1 cup. Bring to a low boil over medium-high heat. 

Combine the cornstarch with the water and whisk the slurry into the pan juices. Transfer to a dish, season with salt and pepper, and serve with the chicken.