Preheat the oven to 375°F. Grease and flour a 9-inch round cake pan.
Slice the oranges in half perpendicular to the stem and remove any seeds. Add them to a food processor and pulse several times, then process until a smooth paste forms.
Add the eggs, almond flour, sugar, baking powder, and salt to the food processor and process until a smooth batter forms.
Pour the batter into the prepared pan and bake until the edges are brown, the top is golden, and a cake tester comes out clean or with moist crumbs, about 45 to 55 minutes.
Let cool in the pan before serving. Top with powdered sugar, marmalade, or whipped cream if desired.
