1. Cut pineapple in half lengthwise. Using a small paring knife, make a cut about 1/2-inch from the pineapple skin, all the way around the pineapple. Remove core and discard. Using a large spoon, remove the pineapple flesh from its skin, making sure to leave about 1/2-inch of flesh all around each pineapple half. Set pineapple shells aside and coarsely chop pineapple flesh.

2. Melt butter in a medium skillet over medium heat. Add onion and garlic. Cook, stirring occasionally, until onion is translucent, about 5 minutes. Add chopped pineapple, bay leaves, sugar, chile powder, and 1/4 teaspoon pimiento arabe. Cook, stirring often, about 15 minutes. Season with salt and set aside to cool. This can be made up to a day in advance; refrigerate until needed and discard bay leaves before using.

3. Position rack in center of the oven and preheat to 400 degrees. Line a baking sheet with parchment paper and set aside.

4. Place adobo sauce in a medium saucepan and bring to a simmer over medium heat, adding water if sauce seems too thick. Place fish and shrimp in a large bowl; season with 1 teaspoon salt and remaining 1/4 teaspoon pimienta arabe and toss to combine.

5. Brush the inside of each pineapple shell with adobo sauce. Divide seafood mixture evenly between each pineapple shell; sprinkle with cilantro. Spread pineapple mixture over seafood, and pour over any remaining adobo sauce. Wrap crowns of pineapple with foil and transfer pineapples to prepared baking sheets. Bake for 20 minutes.

6. Tuck 4 clams into the stuffing of each pineapple; sprinkle cheese over each. Return pineapples to oven and continue baking until clams have opened, filling is bubbling, and cheese is lightly browned, about 20 minutes. Let stand several minutes before serving.