1. For the caramelized pineapple, remove the leaves of the pineapple and cut about 1/2 inch off the top and bottom. Cut away the skin, removing the dark brown "eyes." Cut the trimmed pineapple lengthwise into 4 sections. Remove the tough core and cut the flesh into 1/4-inch pieces.
2. Melt the butter in a medium saucepan over medium-high heat. Add the brown sugar and cook, stirring, until dark and blended, about 2 minutes. Add the pineapple and cook until slightly softened, about 3 minutes. Makes about 2-1/2 cups. Keep tightly covered in the refrigerator until ready to use. Gently warm over low heat before serving.
3. To prepare the waffles, preheat the waffle iron. Whisk both flours with the baking powder, salt and sugar in a large bowl. In a separate bowl, whisk together the butter, buttermilk, eggs and vanilla. Pour the liquid ingredients into the dry ingredients and stir until just combined.
4. Lightly oil or spray the grids of the waffle iron. Spoon 1/2 to 2/3 cup batter into the iron, following manufacturer's instructions. Spread almost to the edges, close the lid and bake until browned and set. Serve hot with a spoonful of the caramelized pineapples on the side.