Preheat your oven to 350°F (175°C) and line an 8x8-inch baking dish with parchment or foil.

Cream together 1/2 cup of unsalted butter and 1/4 cup of granulated sugar until light and fluffy, about 2 to 3 minutes.

Add 1 cup of sifted all-purpose flour and salt, pulsing until the dough resembles small pebbles.

Press dough into the bottom of the prepared dish and bake for 12 to 15 minutes or until golden brown.

Whisk together 4 eggs and 1/2 cup of passion fruit purée until frothy, then mix in sugar and flour until smooth.

Pour the filling over the cooled crust and bake for an additional 25 to 35 minutes until set around the edges.

Let cool at room temperature for 1 hour, then refrigerate for at least 1 to 2 hours before cutting into squares.

Cut into squares and sprinkle with powdered sugar before serving.