Start by placing the whole oranges in a pot of water, bringing it to a boil, and then simmer for about 1 hour.

Once cooked, let the oranges cool, cut them in half, and remove any seeds.

Preheat your oven to 350°F (175°C).

In a blender or food processor, mash the cooled oranges (skin included!) until smooth.

In a large bowl, beat together the eggs and sugar until foamy and increased in volume.

Stir in the orange puree to the egg mixture, followed by the almond meal, pistachios, baking powder, and a pinch of salt. Mix until just combined.

Pour the batter into a greased 9-inch round cake pan. Bake for 50-60 minutes or until a skewer inserted comes out clean.

Allow the cake to cool completely in the pan before inverting onto a plate.

Dust with powdered sugar and sprinkle extra pistachios on top for garnish.