For the Roasted Garlic Glaze:.
Preheat the oven to 325 degrees F.
Cut off the top third of each head of garlic.
Put them on a parchment or foil-lined baking sheet, drizzle 2 tablespoons of the oil over the tops, and sprinkle with 1/2 teaspoon of the salt and 1/4 teaspoon of the pepper.
Turn the garlic cut side down and roast until the cloves are soft and golden brown, about 1 hour.
Remove from the oven and let sit until cool enough to handle.
Into a food processor squeeze each head of garlic gently to release the flesh.
Add the egg yolks, lemon juice, and the remaining 1/2 teaspoon salt and 1/4 teaspoon pepper and puree on high speed.
Add the remaining 1/2 cup of oil in a slow, steady stream and process until the glaze is thick and smooth.
Transfer to an airtight container and refrigerate until ready to use.
(The glaze can be made up to 1 day in advance).
For the Chicken:.
Preheat the oven to 375 degrees F.
Separate the legs& thighs.
Season the chicken on both sides with the Essence.
Heat 1 tablespoon of the oil in each of 2 large ovenproof skillets over medium-high heat.
Place the chicken pieces skin side down in the hot pans and sear for 6 minutes.
Remove from the heat.
Add 2 tablespoons of the butter and 2 sprigs of thyme to each pan, and place in the oven.
Roast for 16 minutes.
Remove from the oven and carefully turn the chicken halves with tongs.
Brush the skin side of each chicken with the garlic glaze and roast skin side up until the skin is crisp, about 10 minutes longer.
For the Lemon Herb Sauce:.
In a small saucepan, bring the chicken stock to a simmer.
Transfer to a blender or food processor.
Add the mustard and process on high speed.
With the motor running, add the lemon juice, olive oil, and herbs, and process until smooth.
Serve immediately. ?