Wash the oranges thoroughly and place them in a large pot covered with water, bringing to a boil and simmering for 60 minutes until very soft.

Drain the oranges and allow them to cool completely, then cut into quarters and remove any seeds.

Place the orange quarters (peel and all) into a food processor and blitz until they form a smooth, thick puree.

Preheat your oven to 350°F (175°C) and lightly grease a 9-inch round springform cake pan.

In a large mixing bowl, beat the eggs and granulated sugar together with an electric whisk until the mixture is pale and frothy.

Gently fold in the almond flour, baking powder, and the prepared orange puree until the batter is uniform.

Pour the mixture into the prepared tin and bake for 45 minutes, or until the top is golden and a skewer inserted into the center comes out clean.

While the cake is baking, combine the honey, water, and lemon juice in a small saucepan and simmer for 5 minutes to create a syrup.

Remove the cake from the oven and prick the surface gently with a fork while it is still warm.

Brush the warm syrup evenly over the top of the cake, allowing it to soak in for at least 10 minutes.

Garnish with toasted sliced almonds before removing from the springform pan and serving at room temperature.