Preheat the oven to 350°F (175°C) and prepare an 8x8 baking dish by lining it with parchment paper or foil.

In a food processor, combine softened unsalted butter and granulated sugar. Pulse for 2-3 minutes until light and fluffy.

Add sifted flour and salt to the creamed butter mixture. Pulse until the dough resembles a crumbly texture, about 1-2 minutes.

Transfer the dough into the prepared baking dish and press it evenly across the bottom. Bake for 12-15 minutes until lightly golden.

In a mixing bowl, whisk together eggs and passion fruit purée. Gradually add granulated sugar and flour, whisking until smooth.

Pour the passion fruit filling over the cooled crust and bake for 25-35 minutes until set with a slight jiggle.

Let the bars cool on the countertop for about an hour, then refrigerate for at least 1 hour or preferably overnight.

Lift the bars out using parchment paper, cut into squares, and dust with powdered sugar before serving.