Place two oranges in a saucepan and add enough water to submerge them. Bring to boil on high heat, then cover with a lid and simmer for approximately 45 minutes or until a knife or skewer easily pierces through the skin.
Thinly slice the third orange and set aside.
Remove the oranges from the water and allow to cool. Cut them into halves to remove the seeds.
Cut the oranges into big chunks and blitz them in a food processor and blitz them into a fine paste.
Grease a 9-inch springform pan and line the base with a parchment (baking) paper circle.
Mix all dry ingredients almond meal, baking powder and salt in a bowl.
Beat the flax eggs and sugar with an electric mixer until pale and fluffy. Add in citrus puree and whisk until well combined.
Gradually mix the dry ingredients with the flax egg and orange mixture, ¼ at a time until a thick batter is formed.
Pour the batter into the cake pan and spread the thin orange slice over the top and sprinkle with the saved 3 tbsp of sugar.
Bake for 50 to 60 minutes until the skewer test comes clean in the middle of the cake.
Allow the cake to cool completely in the tin. Then open the spring form tin and carefully flip the cake on to a plate and remove the bottom, flip back out on to another plate or cake stand.
Dust with icing sugar
Video
Notes
Reduce the sugar quantity to 200gm if you prefer less sweetness in cakesProcess crush whole almonds to make almond meal or use store bought almond mealSprinkle candied orange peel for extra intensity of orange