1) Preheat the oven to 350°F. Bake this cake in either a 9" round or an 8" square cake pan; there's no need to grease the pan.
2) To make the topping: Melt the butter, and mix with the brown sugar, cinnamon, and ginger. Spoon the mixture into the cake pan.
3) Drain and save the juice from the pineapple rings. Space the rings atop the brown sugar mixture: eight pineapple rings will fit in a 9" round pan, and nine pineapple rings in an 8" square pan.
4) Place a cherry in the center of each pineapple ring. If you're using nuts, scatter them in any empty spaces.
5) Follow the box's directions for making the cake batter, but use 2/3 cup of the juice from the pineapple rings instead of the milk called for. If you don't have quite 2/3 cup of juice, use water to make up the difference.
6) Spoon half the batter (about 2 1/2 cups) into the pan, spreading it over the fruit to the edges.
7) Bake the cake for 40 to 45 minutes, until it's firm on top, the edges of the crust are brown, and the internal temperature is between 210°F and 212°F.
8) Remove the cake from the oven, run a spatula around the edge, wait 3 minutes, then turn the pan over onto a serving plate. Wait another 30 seconds, then lift the pan off. If anything sticks to the pan, just scrape it out and spoon it back on the cake. Best served warm.
Yield: 8 to 10 servings.