Preheat your oven to 350°F (175°C) and grease an 8x8-inch baking dish.
In a medium bowl, combine 1 cup flour, powdered sugar, and salt. Add the softened butter and mix until crumbly.
Press this mixture evenly into the bottom of the prepared baking dish to form the crust. Bake for 15 minutes or until lightly golden.
While the crust is baking, in another bowl, whisk together the eggs and granulated sugar until well combined.
Add the passion fruit juice, lemon juice, 1/4 cup flour, and baking powder. Mix until smooth.
Pour the passion fruit filling over the baked crust and return to the oven.
Bake for an additional 20-25 minutes, or until the filling is set and slightly golden on top.
Remove from the oven and allow to cool completely in the pan.
Once cooled, cut into squares and dust with additional powdered sugar if desired.