I recommend weighing the ingredients for this recipe rather than using the cups measurement. Like all of my recipes, this whole orange cake was tested using grams except the baking powder.

Thoroughly wash the skin of the orange and remove the stem, if it's still on. Add around 4 cups of water to a small saucepan and place the whole orange in it. Over medium heat, simmer the orange for 30 minutes until you can pierce the skin with no resistance. Drain the water and allow the orange to cool.

Roughly chop the orange and remove any seeds. Place it in a food processor and process until it forms a paste. It's fine if there are little bits of rind in the paste.

Preheat the oven to 170°C (340°F). Grease or line an 8-inch (20 cm) cake pan with parchment paper (Note 3).

Add the rest of the cake ingredients to the food processor. Process until the mixture is combined and thick. If your batter is runnier, add 1 tablespoon (7g) of potato starch at a time and mix until it forms a thick batter. If in doubt, err towards a thicker batter rather than thinner batter. For this recipe, a thinner batter will make a denser cake.

Scoop the cake batter into a your cake tin. Smooth the top with a spoon or spatula.

Bake the cake for 35-40 minutes (Note 4). The cake is ready when a skewer can be inserted into the middle and there is no wet batter on it (some crumbs are fine). The cake isn't meant to rise much or flatten out but it will 'set'. Allow the cake to completely cool in the cake tin.

To serve, dust the cake with powdered sugar (Note 5). Store leftovers in an airtight container at room temperature for 1 day, in the fridge for 3 days or in the freezer for up to 1 month.