In a small bowl, combine Cajun seasoning, cinnamon, and allspice.
Liberally season skin side of duck with kosher salt. Liberally season flesh side of duck breasts with spice mixture. Reserve any remaining spice mixture to adjust seasoning, if desired.
In a 10-inch cast-iron skillet, place your duck breast skin side down, and cook over medium heat until fat is rendered and skin is golden brown. Turn duck pieces, and increase the heat to high. Cook for 2 minutes, making sure your duck still looks quite reddish-pink, indicating rare to medium-rare. Remove duck from skillet, and set aside; reserve drippings in pan.
Reduce heat to medium, add your bacon, and cook, stirring occasionally, until crisp. Remove bacon from the skillet, and let drain on paper towels. Reserve about ¼ cup drippings in skillet.
In the same skillet, add apples in one layer, and cook over medium-high heat, stirring occasionally, getting color on at least one side of your apples, about 4 minutes. Once slightly softened, remove from the skillet, and set aside.
Add yellow onion, sliced green onion, and garlic to the skillet, and cook over medium-high heat, stirring occasionally, until they soften and begin to turn golden. Add butter, and cook, stirring occasionally, until it melts. Reduce heat to medium-low heat; add brown sugar, and cook, stirring constantly, until melted. Increase heat to high; add bourbon, and scrape the bottom of the skillet with a wooden spoon to release any browned bits. Carefully ignite bourbon, and cook, shaking skillet occasionally, until flame subsides. Cook, stirring occasionally, until sauce is reduced. Taste sauce and adjust seasoning, if necessary.
Slice duck breast into ¼-inch strips.
Increase heat to high, and add reserved apples and duck strips with any remaining juices to the skillet. Cook, stirring constantly, until the mixture comes together into a sauce. Adjust seasoning to taste with salt and black pepper. Turn off heat, and add bacon, chopped green onion (if using), and vinegar, gently folding together. Serve on top of white rice or on a platter with toothpicks to enjoy as an appetizer.
Recipe by Louisiana Cookin' at https://louisianacookin.com/dads-duck-dinner/