Combine 1/4 teaspoon of cinnamon and the next four ingredients (through ground cloves) in a small bowl.
Slice the tenderloin into 12 medallions, about 1/2-inch thick. (Lightly pound for even thickness, if needed.) Rub the spice mixture all over the pork and place on a plate. Cover and refrigerate at least 1 hour (may be made 1 day ahead). Let stand at room temperature 30 minutes before cooking.
Preheat the oven to its lowest temperature (to keep the pork warm).
Heat a large, heavy (preferably cast-iron) skillet over medium-high heat and brush with 1 tablespoon of olive oil. Season the pork medallions with salt and sear until nearly cooked through, about 3 minutes per side. Transfer to a plate and keep warm in the oven.
Add the butter to the skillet, swirling to coat. Add the shallot and sauté 1 minute. Add the apple and pear slices and season with salt and pepper. Sprinkle the remaining 1/2 teaspoon of cinnamon over the mixture and stir well to combine. Cook slowly until the fruit slices begin to soften, 5 minutes.
Carefully add the wine to the skillet (it will sizzle) and cook until nearly evaporated and the fruit is tender, 2 minutes.
Return the pork and any accumulated juices to the pan and combine with the fruit. Garnish with parsley and serve.
Warm, aromatic spices like cinnamon, paprika, allspice, and clove make a flavorful rub for lean pork tenderloin—and a cast-iron skillet with a light coating of olive oil is all it takes to sear the meat quickly and lock in tenderness and taste.
Most whole spices are easy to grind in a spice mill, but cloves can sometimes clog the grinder or retain larger pieces. To remedy that, simply place whole cloves in a small plastic bag and lightly pound them with a meat mallet to a powdery consistency.
Cook the apples and pears in the same skillet to keep the preparation simple—and to pick up any deliciously spicy morsels left behind by the pork.