Hatch score Duck Breast through the skin, just to the meat. Sprinkle Kosher Salt and Pepper inside the hatch marks and place duck breast on a rack of a roasting pant in the refrigerator uncovered overnight.
When ready to cook, choose a heavy bottomed pan - my choice is cast iron. On medium heat melt 1/4 stick salted butter in your pan and place duck skin down. Do not flip or move duck breast until you see skin is is brown. Then flip over, wait one minute and thyme stems, garlic cloves and 1/2 of them orange zest. Baste breast with a spoon.
Once your duck is 125°, which is rare, or 130 which is medium rare, remove from the heat to your serving platter to rest while you make the blueberry sauce.
In the same pan that you cooked the duck in remove any excess fat, garlic and thyme stems. On medium heat add blueberries and cook for 3 minutes stir in the reserved orange zest, once fragrant add a large pinch of fresh thyme leaves and deglaze the pan with 2 TBL of cognac and 2 TBL of fresh orange juice.
Once the alcohol sizzles off add 2 tsp of brown sugar, stir lightly serve over duck.