Heat a 9-inch skillet over medium heat and melt 2 tablespoons butter. Add the slices of pineapple in a single layer and sprinkle the brown sugar over the fruit. Cook until the pineapple browns slightly, 2 to 3 minutes. Flip the pineapple slices. Turn off the heat and keep warm.
Whisk together the buttermilk, vanilla, eggs and the remaining 6 tablespoons butter in a medium bowl until smooth. Use a rubber spatula to stir in the flour, granulated sugar, salt, baking powder and baking soda until completely smooth. (The batter will be fairly stiff.) Pour the batter over the pineapple.
Transfer the skillet to the center of the oven and bake until a toothpick inserted in the center of the cake emerges clean, 40 to 45 minutes. Cool for about 10 minutes before carefully unmolding onto a serving platter. (See Cook's Note.)
For the caramel: Combine the granulated sugar, corn syrup, lime juice and 1/4 cup cold water in a medium stainless saucepan. Stir in the pink peppercorns and bring to a gentle simmer. Cook until the sugar is dissolved, then cook, 10 minutes. Set aside to cool slightly. When the cake is unmolded, pour the caramel over the cake.
If you cool the cake and it won't unmold, warm the skillet over low heat until it dislodges.
This recipe has been updated and may differ from what was originally published or broadcast.