Because turkey's not just for Thanksgiving!
In a Dutch oven or a large skillet with a lid, heat 4 tbsp. butter over medium-high. When the butter foams, add the cabbage and onions. Stir in the sage; season with salt and white pepper. Cover and cook, stirring occasionally, until the cabbage wilts and begins to brown, about 10 minutes. Stir in the apples, sugar, nutmeg, and 1 cup stock. Partially cover and cook, stirring occasionally, until the apples are just tender, about 10 minutes more.
Meanwhile, in a large skillet, heat the oil, two turns of the pan, over medium-high. Season the turkey cutlets with salt, pepper, and poultry seasoning. Working in batches, add the cutlets to the skillet and cook, turning once, until browned on both sides, about 3 minutes per side. Transfer to a platter.
Add the remaining 4 tbsp. butter to the skillet. When the butter foams, stir in the shallot; season with the coarsely ground pepper, rosemary, and salt. Sprinkle in the flour; whisk to combine. Whisk in the brandy, vinegar, cider, and the remaining 2 cups stock. Cook, whisking often, until the gravy thickens, about 8 minutes. Stir in the Worcestershire. Slide the cutlets into the gravy. Reduce the heat to a simmer and cook until the turkey is cooked through, 2 to 3 minutes more.
Divide the toast among 4 plates. Top with the turkey and gravy; garnish with parsley. Serve the cabbage and apples alongside.