In a large saucepan over medium-high heat, combine the apples, wine, water, sugar, ginger, fennel, cinnamon, nutmeg, star anise, and 1 tablespoon of butter and bring to a simmer. Cover and cook over moderately low heat, stirring occasionally, until the apples are tender, about 12 minutes. Uncover and cook, stirring, until the liquid is almost evaporated, about 5 minutes longer. Discard the cinnamon stick, and star anise.
In a large skillet, heat the olive oil until shimmering. Season the pork medallions with salt and pepper. Add them to the skillet and cook over medium-high heat until browned on both sides, about 10 minutes. Transfer the pork to a plate and keep warm.
Return the skillet to medium-high heat, add the remaining 4 tablespoons of butter and the rosemary. Cook about 2 minutes, stirring, until the rosemary butter is browned and fragrant. Discard the rosemary sprigs. Spoon the applesauce onto plates, top with the pork medallions. Drizzle the rosemary butter over the top and serve.
Suggested side dishes: Butternut squash, stuffing, asparagus, or Brussels sprouts