FOR THE TOPPING:

1. Preheat oven to 350°.
2. Prepare 2-9 x 5″ loaf tins by spreading some butter along the sides. Set aside.
3. *With a Microplane (affiliate link) grater, zest the blood oranges. With a sharp knife, slice off the root end and stem end, then remove the skin from the orange, following the curve. Try to save as much juice as you can, and add the juice to the butter-sugar mixture.
4. In a saucepan, over medium-high heat, add the butter and melt until it becomes bubbly, foamy, and lightly browned (keep an eye on it!). Add the brown sugar and stir until melted and evenly distributed for about 2 minutes. Equally pour into the prepared loaf tins, then arrange the blood orange slices on top of the mixture in each pan, overlapping slightly. You may wind up not using all the orange slices, depending on their size.

FOR THE CAKE:

1. In a medium-size mixing bowl, whisk together the flour, cornstarch, baking powder, baking soda, and salt. Mix in the zest from oranges and set aside.
2. With a handheld or stand mixer fitted with a paddle attachment, beat the olive oil and sugar on high for about 1 minute. Scrape down the sides and up the bottom of the bowl with a rubber spatula.
3. With the mixer on medium speed, beat in the eggs, one at a time, until combined. Add vanilla and mix well.
4. Turn the mixer to low, alternate adding half the flour mixture with half the buttermilk, repeat. Work quickly (but gently) as to not over mix the batter (or it will be a tough cake). Scrape down the sides to check there isn’t any dry flour at the bottom of the bowl. The batter should be slightly thick.
5. Equally pour the batter evenly over topping, spread with an offset spatula to the edges.
6. Bake for about 30-35 minutes. The cakes are done when a toothpick inserted into the centers comes out with a couple of moist crumbs. Check around 25 minutes for doneness.
7. Remove the cakes from the oven and cool on a wire rack for about 15 minutes. Using hot-pads or towels to protect yourself from juices overflowing and the hot pan, invert the cakes onto a serving platter. Cool the cakes completely at room temperature before slicing and serving with a dollop of creme fraiche or whipped cream.