Place unpeeled oranges in a saucepan. Cover them with water and bring it to a boil. Boil the oranges for 10 minutes and drain. Repeat this process twice more.

After the third boil, let the oranges cool down. Once they're cool enough to handle, chop the oranges into 1-inch pieces.

Add the chopped oranges into a food processor or high-power blender and blend until you get a marmalade-like mixture.

Preheat your oven to 320F. Line a 9-inch springform pan with baking paper, covering both the bottom and sides.

In a bowl, beat the eggs and sugar together. Then add the orange mixture, almond flour, and baking powder. Stir until the batter is smooth.

Pour the batter into the prepared cake pan. Bake for 60 minutes or until a toothpick inserted in the center comes out clean.

Let the cake cool completely before slicing and serving.