Preheat your oven to 350°F [180°C].
Butter the bottom and sides of an 8-in [20-cm] cake pan and line the bottom with parchment paper.
Whisk together flour, ground nuts, baking powder, and salt in a medium bowl.
Whisk eggs in a large bowl, then add olive oil, sugar, vanilla extract, orange zest, and orange juice.
Whisk in the flour mixture.
Pour the batter into the prepared pan and eliminate air bubbles.
Bake for 25-30 minutes until golden brown and a toothpick comes out clean.
Let the cake cool completely, then invert onto a serving platter.
Dust the cake with powdered sugar before serving.