1. Preheat oven to 350°F (175°C) and line a 9-inch round cake pan with parchment paper.

2. In a saucepan, combine 1 cup sugar and 1 cup water. Bring to a gentle simmer until sugar dissolves.

3. Add thinly sliced oranges and simmer 15–20 minutes until translucent. Remove and cool slightly.

4. Arrange candied orange slices in a single layer on the bottom of the prepared pan.

5. In a large bowl, whisk eggs and 3/4 cup sugar until slightly thickened.

6. Add olive oil (or melted butter), orange zest, and vanilla extract. Mix until smooth.

7. In a separate bowl, combine almond flour, baking powder, and salt.

8. Fold dry ingredients into wet mixture until fully incorporated.

9. Pour batter gently over arranged oranges and spread evenly.

10. Bake 35–45 minutes until golden and a toothpick inserted in center comes out clean.

11. Cool 15 minutes, loosen edges, invert onto serving plate, and remove parchment paper.

12. Brush with reserved orange syrup and garnish with sliced almonds or powdered sugar if desired.