Blood orange and olive oil upside-down cake

Set a rack in the center of the oven and preheat to 350F.

Brush the springform pan's bottom and sides with olive oil, line the bottom with a parchment round, smooth out air bubbles, and oil the parchment thinly.

Slice a pole off each blood orange to expose the fruit and cut into rounds no thicker than an eighth of an inch with a sharp knife, removing seeds; squeeze the ends into a bowl.

Whisk the sugar and 2 tbsp juice into a thick mixture without dissolving the sugar, and spread it over the bottom of the pan.

Lay the slices from one edge, overlapping by about half, in rows around the pan until covered; press them into a flat layer.

Whisk the cake flour, semolina, baking powder and kosher salt.

Combine the Grand Marnier, vanilla, and the orange and lemon zest.

Whip the eggs and remaining sugar with the whisk attachment, low then medium-high to high, 4 to 5 minutes until pale, thick, about tripled and at the ribbon stage.

Stream in the olive oil very slowly down the side of the bowl so it emulsifies and stays thick.

On low speed, add the dry ingredients in three parts alternating with the wet in two, starting and ending with dry; finish by folding by hand with a flexible spatula.

Pour the batter slowly over the fruit from one end to the other.

Bake at 350F for 35 to 45 minutes until risen, golden brown, springy, and a cake tester comes out clean.

Cool in the pan about 15 minutes, run an offset spatula around the edge, and flip out while still warm so the sugars do not harden and stick.

Wipe away any cake that crept over the slices; optionally paint pan juices or strained orange marmalade over the top for shine. Let cool.