Combine all the topping ingredients (melted butter, brown sugar, cinnamon, allspice, ginger, salt) using a medium bowl. Spread this mixture evenly into the bottom of the prepared baking pan. I arrange the apples in a spiral for a prettier presentation, but this is optional.
Pour batter over the apples.
Bake for 30 minutes and then cover top of the pan with aluminum foil. Continue baking for 25-30 more minutes, or until a toothpick inserted into the center of the cake comes out mostly clean. (Tip: If using a pan with a removable bottom, put a sheet pan on the oven rack underneath to catch any potential drips.)
Let cake cool in pan for 5 minutes.
Run a table knife around edge of the cake and then place a serving plate upside-down on top of the pan. Invert the cake onto the serving plate. (Note: If the parchment paper comes out with the cake, simply peel it off the top and discard.)
Let cake cool for 25-30 minutes before slicing and serving.