Prepare the brine first. Place 1 quart of water in a pan over medium heat. Stir in 6 savory sprigs, 5 cloves garlic, 1 tablespoon peppercorns, 1/2 cup kosher salt and 1/4 cup brown sugar. Cook just until salt and sugar dissolve. Turn off heat and add remaining quart of cool water. Allow brine to cool to room temperature.

Place chicken in a gallon size resealable bag. Place into a bowl in case there are any leaks. Carefully pour brine into the bag. You may not need all the brine, you just want to make sure the chicken is covered. If you don't use all the brine just make sure that all of the garlic, savory and peppercorns make it into the bag with the chicken. Place chicken in refrigerator for at least 6 hours or overnight.

Remove chicken from brine. Discard brine and gently rinse chicken. Pat dry.

Place chicken, breast side down, on a working surface and using kitchen shears, cut the backbone out. Turn the chicken over and firmly press down on the breastbone to flatten the chicken.

Combine remaining 1 tablespoon fresh summer savory, 1 1/2 teaspoons kosher salt, black pepper and avocado oil together in a bowl. Mix well then rub over the chicken.

Preheat oven to 425 degrees.

Heat a cast iron, or other oven safe skillet over medium heat. Place chicken skin side down. Place a piece of aluminum foil over the top of the chicken and place another cast iron skillet (or other heavy bottomed pan) on top to weigh the chicken down. Cook for 7 minutes.

Gently turn chicken over. Scatter mushrooms around the chicken and place in preheated oven.

Cook at 425 degrees for 10 minutes. Reduce heat to 350 and continue cooking for another 30 - 35 minutes or until a meat thermometer inserted reaches 165 degrees.

Remove chicken and allow to rest 5 minutes before carving. Spoon mushrooms and pan juices over the top of carved chicken. Serve.