Prepare Chicken: Butterfly each chicken breast by slicing horizontally to create a pocket without cutting completely through. Pat dry to help browning.
Sear Chicken: Heat a large skillet over medium heat and melt 2 tablespoons butter. Add chicken breasts and cook for about 4–5 minutes per side until golden brown. The chicken will finish cooking in the oven.
Transfer Chicken: Move the browned chicken to a foil-lined baking sheet and set aside.
Make Filling: In a mixing bowl, combine panko bread crumbs and 1 tablespoon melted butter. Add diced Manchego cheese, diced apple, and diced ham. Stir until evenly mixed.
Stuff Chicken: Open each chicken pocket and spoon several tablespoons of filling inside each breast. Divide remaining filling evenly over the tops of the chicken.
Bake Chicken: Bake in a preheated 375°F oven for 12–15 minutes, or until the chicken reaches 165°F internally and the topping becomes lightly toasted.
Start Apple Sauce: Return the same skillet to medium heat. Pour in the apple juice and scrape up browned bits from the pan for flavor.
Finish Sauce: Stir in the applesauce and ground cumin. Simmer for 5–7 minutes until slightly thickened. Reduce heat to low and keep warm.
Cook Tomatoes: Heat olive oil in a clean skillet over medium heat. Add cherry tomatoes and cook for about 2 minutes until just softened.
Wilt Spinach: Add baby spinach to the tomatoes and toss with tongs for 1–2 minutes until just wilted.
Season Salad: Sprinkle kosher salt and black pepper over the spinach mixture and toss gently to combine.
Add Parmesan: Remove skillet from heat and sprinkle shaved Parmesan cheese over the warm spinach so it melts slightly.
Plate Dish: Spoon the apple sauce onto a serving platter or individual plates.
Serve Chicken: Place baked Chicken Manzana over the apple sauce.
Serve Salad: Arrange the wilted spinach salad alongside the chicken and serve immediately.