Rub the duck breast with the kosher salt and cracked pepper. Wrap in plastic wrap and refrigerate for 24 hours.
Remove the duck breast from the refrigerator and rinse thoroughly with cool water to remove the salt and pepper. Place the meat in a small glass container and cover with 1/2 cup of the molasses, the garlic cloves, juniper berries, and whole peppercorns. Cover and refrigerate for 48 hours.
Remove the duck from the refrigerator and drain off the marinade.
Preheat the oven to 400ºF.
Heat 1 teaspoon of the olive oil in a large ovenproof sauté pan over medium heat. Place the duck breast, skin side down, in the pan and cook until the skin is crispy and brown, 10 minutes. Turn the meat over and cook for 10 minutes more. Transfer the pan to the oven. Roast for about 5 minutes for medium rare; 8 minutes for medium; 10 minutes for well done. Remove the pan from the oven, transfer the meat to a cutting board, and let it rest for about 2 minutes before cutting at an angle into 1/4-inch-thick slices.
In the sauté pan, over low heat, combine the remaining 2 tablespoons molasses, the shallots, minced garlic, mustard, the remaining 2 tablespoons olive oil, and the vinegar. Whisk until the mixture is emulsified, about 2 minutes. Season with salt and pepper. Remove from the heat, add the spinach, and toss to coat evenly.
To serve, mound the greens in the center of the plate. Arrange the duck slices around the greens, and sprinkle with the pecans, red onion, and blue cheese.
Yield: 4 servings