1. Boil the Oranges: Place the whole, unpeeled oranges in a pot and cover with water. Bring to a boil, then reduce heat and simmer for 1 hour to 1.5 hours until they are very soft. Drain and let them cool completely. (This removes the bitterness from the pith).

2. Preheat & Prep: Preheat your oven to 350°F (175°C). Grease a 9-inch (23cm) springform pan and line the bottom with parchment paper.

3. Process Oranges: Once cooled, cut the oranges into quarters and remove any seeds. Place the chunks (peel included) into a food processor and blend until you have a smooth, thick orange puree.

4. Mix Batter: In a large bowl (or in the processor with the orange pulp), add the eggs and sugar. Pulse or whisk until well combined. Add the almond flour and baking powder. Mix until you have a uniform batter.

5. Bake: Pour the batter into the prepared tin. Bake for 45–60 minutes. Check at 45 minutes; if the top is browning too quickly, cover loosely with foil. The cake is done when a skewer inserted into the center comes out generally clean (it will still be moist).

6. Cool: Let the cake cool completely in the tin. It is very fragile while hot. Once cool, remove the sides of the springform pan.

7. Serve: Dust with powdered sugar or top with flaked almonds before serving.