Preheat oven to 400°F (200°C). Line a baking sheet with parchment paper.

Using a large sharp knife, cut top and bottom off pineapple. Cut pineapple lengthwise into fourths. Cut core out of each fourth. Using a smaller knife, carefully cut flesh away from rind, wasting as little as possible. Cut each fourth lengthwise down center, and cut crosswise into ½-inch slices. (You should have flat trapezoid-shaped pieces.)

In a medium bowl, combine pineapple, rum, brown sugar, melted butter, and vanilla bean paste, gently tossing to coat. Pour onto a rimmed baking sheet, spreading pineapple into a single layer.

Bake until softened, 15 to 20 minutes. Transfer mixture to a heatproof bowl, and let cool completely.