Cover a cake baking form with baking paper.

Heat the oven to 170 C.

Separate 5 egg whites from yolks in two different bowls.

In the bowl with the yolks, add the 6th whole egg plus 250 g of sugar, and the grated zest of 3 oranges. Beat the egg yolks until the sugar dissolves and the mixture becomes foamy.

Add the almond flour and mix with a spatula, until you get a dense and crumbly dough.

Whisk the egg whites separately until you get stiff foam.

Start to introduce the whites into the yolk mixture, bit by bit. Mix well but gently, until it is completely incorporated. Try to keep it as fluffy as possible.
Transfer mixture to a lined cake baking dish and put it in the oven for 45 minutes or until it turns golden around the edges.

Meanwhile prepare the syrup.

In a saucepan, add 50 g of remaining sugar, the juice of 3 oranges and water.

Bring to a boil on low heat. Remove from the heat and mix well to dissolve the sugar, while also adding the sage leaves. Let it infuse until the cake is ready to be taken out of the oven.

After removing the cake from the oven, pierce it while it is still warm with a toothpick, on its entire surface. Pour over the infused syrup and leave it aside until it cools completely.

Decorate with sage leaves and/or orange slices.