Butterfly the chicken: Remove the chicken giblets. Gently pat it dry with clean paper towel. Place the whole chicken breast side down over a secured large cutting board. Use a pair of kitchen shears to cut down each side of the back bone (i.e.spine) from cavity up to the neck. Save the backbone for later use (p.s. great for chicken stock). Make a shallow incision cut in the cartilage on the back of the breast bone and use your hands to gently press both sides down to flatten the bird.
Season the chicken: Mix well salt, pepper, garlic, herbs, and olive oil in one bowl. Flip the bird (skin side up) and use your fingers to gently separate the skins from the meat to create small pockets. Be careful not to tear the skin. Tuck the wings behind the breast. Stuff the herb mixture under the skin and use your hands to gently spread the herbs as even as you can. Make sure to season the outer interior and the back of the bird. Drizzle with half of one whole lemon juice. Marinate overnight in a large flat container, breast side down to soak up more juice flavor.
Bake: Preheat oven to 425 F (regular oven) or 400 F (convection oven). Place the bird (skin side up) on top of a wire rack over a large sheet pan, lined with parchment paper. Bake for 30 minutes. Rotate the sheet pan and loosely cover the wings and any other spots that get brown too quickly with foil paper so they won’t get burnt. Bake additional 20 minutes or until the breast meat reaches 150 F and the thigh meat reaches 175F when using a read thermometer.
Remove from the oven. Let the bird cool for 10 minutes before carving.
To make chicken gravy: In a saucepan over medium-low heat, add 1 tbsp chicken dripping from the sheet pan. Whisk in flour until fragrant (1 to 2 minutes). Slowly whisk in chicken stock. Reduce heat to low. Bring gravy to a simmer, stir often and cook until thick enough to coat the back of a spoon (about 3-4 minutes). Season with salt, pepper, and lemon juice to taste. Strain through a fine-mesh sieve into a gravy boat.
If you don't have time to marinate the chicken overnight, try marinate the chicken for at least 30 minutes before roasting.