Prepare the COMPOUND BUTTER.
In a medium bowl, combine softened butter, lemon zest, lemon juice, garlic, parsley, salt, and pepper.
Using a fork, mash and stir until well combined. Set aside.
FOR THE TURKEY
Rinse the turkey and pat it dry with paper towels.
Season inside of turkey cavity generously with salt and pepper.
Fill the cavity with halved bulb of garlic (use both halves), quartered onions, and all the sprigs of fresh herbs.
Using your fingers OR the long handle of a wooden spoon, separate the skin from the breast meat, starting at the top of the breast and slide to the right and left, then work your way down.
With your fingers, grab small dollops of the compound butter and rub 2/3 of the butter mixture under the turkey’s skin.
Then, spread the rest of the compound butter around and over the top of the skin.
Tie up the legs with kitchen twine; tuck the wing tips under; transfer turkey to a roasting pan fitted with a rack.
Place a meat thermometer into the bird, beneath the drumstick, deep into the dark meat.
Pour 4 cups of chicken broth inside the roasting pan and transfer turkey to the oven.
Place turkey in the oven and immediately lower the temperature to 350F.
Roast for 40 minutes; remove from oven - close the oven door so you don’t let out the heat – baste the turkey with the drippings from the bottom of the roasting pan.
Place a piece of foil over the turkey breast area and put turkey back in the oven. Cook for 2 1/2 to 3 hours, basting every 40 minutes. Turkey is done when thermometer reads 170F at the thigh, and 160F at the breast.
Remove turkey from the oven; transfer it to a cutting board, cover loosely with foil and let rest for at least 30 minutes.
In the meantime, prepare the MAPLE GRAVY
Pour out the pan juices into a heatproof bowl and skim off the fat.
Set the roasting pan over 2 burners on high heat until sizzling.
Add 1 cup of the pan juices and bring to a boil, scraping up all the browned bits stuck to the bottom. Add the liquid back into the bowl with the remaining pan juices and set aside.
Melt butter in a saucepan and whisk in flour for 1 minute. Add 2 cups of the pan juices to the saucepan and cook (add water or broth if needed to make 2 cups), whisking, until the gravy is thickened; about 5 minutes. Stir in the maple syrup and season with salt and pepper.
Strain the gravy into a gravy boat.
Carve the turkey and serve with the gravy.