Preheat your oven to 350°F (175°C) and grease an 8×8-inch baking pan.

In a medium mixing bowl, combine the melted unsalted butter, all-purpose flour, and granulated sugar. Stir until the mixture resembles coarse crumbs.

Press the mixture evenly into the bottom of your prepared pan and bake for 10–12 minutes until lightly golden.

In a separate bowl, whisk together the eggs, filling sugar, drained crushed pineapple, and vanilla extract until smooth.

Fold in the shredded coconut if desired, then pour the pineapple mixture evenly over the slightly cooled crust.

Bake for an additional 20–25 minutes until the filling is set and edges are light golden brown.

Allow the bars to cool completely in the pan before slicing into squares and dusting with powdered sugar.