Blood oranges upside-down cake

Directions

1. Line a 9-inch round cake pan with parchment.
2. With a sharp knife, slice ends off oranges, following the curve of the fruit, cut away peel and white pith, slice oranges crosswise into rounds and remove any seeds and set aside.
3. Melt 3 tbs butter and pour over bottom of prepared pan, sprinkle with 1/4 cup sugar, arrange sliced oranges over the sugar in a pan and set aside.
4. Beat the eggs and 3/4 cup sugar for 6 minutes, add in the flour and melted butter.
5. Pour batter over oranges, make sure not to disturb the fruit, smooth the batter.
6. Place cake in oven on the middle rack. Bake on 350F for about 40 minutes.
7. Test the cake with a toothpick, making sure it is cooked in the middle.
8. Let it cake cool for about 30-40 minutes.
9. With the knife loosen edges along the pan.
10. Put a large platter face down over cake pan and flip.
11. Brush cake with melted orange jam (1 cup orange jam, 2 tbs water).