Preheat your oven to 350°F and line an 8×8-inch baking pan with parchment paper.

To make the crust, cream the softened butter and sugar together until smooth in a large mixing bowl. Add in the flour and salt, and continue mixing until a crumbly dough forms.

Press the dough evenly into the bottom of the prepared baking pan, then bake for 15-18 minutes or until lightly golden.

While the crust is baking, make the filling by whisking together the blood orange juice, zest, flour, and baking powder in a mixing bowl.

In a separate bowl, beat the eggs and sugar together until pale and frothy, then fold in the dry ingredients until well mixed.

Pour the filling mixture over the baked crust and return the pan to the oven to bake for an additional 20-25 minutes, or until the filling is set.

Allow the bars to cool completely before removing them from the pan and dusting with powdered sugar.

Cut into squares and serve chilled.