Blood Orange Upside Down Cake

In a saucepan, combine ½ cup (120 ml) water and ⅔ cup (120 g) sugar and bring to a gentle simmer, stirring until the sugar dissolves. Add the 2 thinly sliced blood oranges and cook for about 7 minutes, until the slices soften and look glossy. Remove the slices carefully, place them on parchment paper, and set aside.
Separate the 3 eggs, placing the yolks in one bowl and the whites in another. In a large mixing bowl, whisk the 3 egg yolks, zest of 1 orange, and 3 tablespoons (40 ml) of orange juice until smooth and well blended. Add 2 tablespoons (30 ml) milk, 3½ tablespoons (50 ml) extra virgin olive oil, 1 teaspoon vanilla extract, ⅓ cup (80 g) sugar, and ¼ teaspoon salt, whisking until the mixture is evenly combined.
Gradually sift in ¾ cup (100 g) flour, stirring gently to avoid lumps and create a smooth batter.
Arrange the candied blood orange slices evenly across the bottom of a 20 cm cake mold. In a separate bowl, beat the 3 egg whites until stiff peaks form, then gently fold them into the batter in batches until fully incorporated.
Pour the cake batter over the candied orange slices in the mold.
Pour the batter over the orange slices and smooth the top. Bake in a preheated oven at 340°F / 170°C for about 35 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cake to cool slightly, then carefully invert it onto a serving plate to reveal the glossy blood orange topping.