Step 1: Prepare the Oranges

Start by boiling the oranges. Place the two whole oranges (unpeeled) in a large pot of water, bring to a boil, and simmer for 1-2 hours until soft. Once cooked, drain the water and let the oranges cool completely. Cut them open, remove any seeds, and blend the oranges (peel included) into a smooth purée.

Step 2: Preheat the Oven

Preheat your oven to 180°C (350°F). Grease and line a 23cm (9-inch) round cake tin with parchment paper.

Step 3: Mix the Cake Batter

In a large mixing bowl, beat the eggs and caster sugar together until light and fluffy. Add the ground almonds, baking powder, and lemon zest (if using). Then, fold in the orange purée, mixing gently until all the ingredients are well combined.

Step 4: Bake the Cake

Pour the batter into the prepared cake tin and smooth the top with a spatula. Bake in the preheated oven for 45-50 minutes, or until a skewer inserted into the center of the cake comes out clean. If the top of the cake starts to brown too quickly, cover it loosely with foil after 30 minutes of baking.

Step 5: Prepare the Orange Glaze (Optional)

While the cake is baking, you can prepare the orange glaze. In a small bowl, mix the icing sugar with 2-3 tablespoons of orange juice until smooth. The glaze should be pourable but not too runny.

Step 6: Cool and Glaze the Cake

Once the cake is fully baked, remove it from the oven and let it cool in the tin for about 10 minutes before transferring to a wire rack to cool completely. Once cooled, drizzle the orange glaze over the top of the cake for an extra burst of citrus flavor.

Step 7: Serve

Slice and serve the cake as is, or with a dollop of whipped cream or a sprinkle of icing sugar for a beautiful presentation. This cake pairs wonderfully with a cup of tea or coffee.