Preheat & Prep: Preheat your oven to 350°F (175°C). Grease a 9x9-inch baking pan with cooking spray or a little extra butter.

Combine Ingredients: In a large mixing bowl, whisk together the crushed pineapple (with its juice), granulated sugar, eggs, cornstarch, and vanilla extract. Whisk until the cornstarch is completely dissolved and the mixture is smooth.

Pour: Transfer the pineapple mixture into your prepared baking pan, spreading it out in an even layer.

Add Toppings: Distribute the thin pats of butter evenly across the surface of the mixture. Sprinkle the ground cinnamon evenly over the top.

Bake: Bake on the center rack for 45 minutes. The bake is done when the edges are bubbling and golden brown, and the center is set.

Cool & Serve: Remove from the oven and let the dish rest for 5 to 10 minutes before serving. Enjoy warm!