Preheat oven to 350°F. Lightly grease a 9x9 inch baking dish and set aside.
In a large bowl, stir together the pineapple with juices, sugar, eggs, cornstarch, and vanilla until fully combined.
Pour pineapple mixture into prepared baking dish. Dot the top with butter pats and sprinkle with cinnamon.
Bake for 45 minutes, until edges are bubbly and top is lightly golden.
Allow to cool 5-10 minutes before serving warm, or chill completely to serve cold.
Top with whipped cream or vanilla ice cream, if desired.