Directions

1. Place a rack in middle of oven; preheat to 350°. Melt butter in a 10-inch (as measured across the bottom) cast-iron or other ovenproof skillet; set aside. Whisk flour, salt, cinnamon, baking soda, and baking powder in a medium bowl.
   
2. Whisk molasses, egg, ginger, and 1/4 cup sugar in a large bowl. Whisk in sour cream, then milk. Gradually whisk in dry ingredients, then 3 tablespoons melted butter from skillet. Set aside.
   
3. Place 1 apple on a work surface stem up. Cut a large piece of apple from 1 side, leaving core behind. Rotate apple and repeat twice for a total of 3 large pieces (a triangular core will remain). Repeat with remaining apples.
   
4. Add remaining 1/4 cup sugar to butter in skillet. Cook over medium-high heat until sugar begins to caramelize, 2-3 minutes. Add apples; stir to coat. Cook apples rounded sides down for 3 minutes, then turn over and cook flat sides down until beginning to soften, about 5 minutes longer. Space apples evenly in skillet flat side down and pour cake batter over.
   
5. Transfer skillet to oven. Bake until a cake tester inserted into the center comes out with a few moist crumbs attached, 30-40 minutes. Let cake cool in skillet for 10 minutes, then carefully invert onto a plate. Serve cake warm or at room temperature.