Collapsing chocolate orange (no wheat) cake

Some would say that this cake is not a real cake as it is difficult, but possible to cut as it collapses, but I just love it. Very, very much. With sweetness from chocolate, bitterness from oranges, some touches of salt, it just melts many hearts. 

Ingredients

400 g organic oranges (300 g puree)
200 g butter, cut into pieces
200 g 70% chocolate, pieces
5 large eggs, yolks and whites separated
145 g light brown sugar, for egg yolks
90 g almond flour
40 g polenta
30 g cacao powder
flaked sea salt to sprinkle on top
45 g caster sugar for egg whites

Prepare

Place oranges into a pot, pour over the water so that oranges are covered and boil for an hour. Drain and let cool (I let them cool for 12h). Afterwards, place them into a blender and blend until a rough puree consistency.

Preheat the oven to 160°C and line the bottom and grease the sides (with butter) of a 23 cm round cake tin.

Melt the butter and chocolate over simmering water (do not let the water touch the bowl). Take it off and let it cool for a while.

Whisk the egg yolks with the sugar for about 7-10 minutes until thick and pale. Add flour, polenta, cacao, and oranges and mix with spatula. Pour into the melted chocolate mixture and mix just to combine.

With a stand mixer, whisk the egg whites on medium speed until they are frothy and add the caster sugar, whisking on high speed, until you have stiff glossy peaks. Fold the whites into the chocolate mixture in two parts being careful not to knock all of the air out. Pour into the pan, sprinkle some salt over, and bake for 45 minutes. Then turn off the oven, leave the door ajar, and let it rest for 30 minutes. 

Take out and let it cool in the pan. It will crack, but that's what makes it beautiful. When it is cool, place in the fridge and eat only after ~2h, but the best is 24h, sprinkling with a good amount of cacao powder.