Preheat the oven to 350°F (175°C) and prepare an 8x8-inch baking pan with aluminum foil and cooking spray.

In a medium bowl, combine softened unsalted butter, all-purpose flour, granulated sugar, and a pinch of salt. Mix until crumbly, about 3-4 minutes.

Press the remaining crumb mixture into the bottom of the prepared pan and bake for 10 minutes or until lightly golden.

Whisk together the egg, granulated sugar, sour cream, vanilla extract, and a little flour in a separate bowl until smooth.

Pour the filling over the warm crust and spread it out evenly before adding the drained pineapple chunks.

Sprinkle the reserved crumb mixture on top of the pineapple layer.

Bake for an additional 35 minutes until the edges are set and the top is golden brown.

Allow the bars to cool completely in the pan on a wire rack for at least 1 hour before slicing.