Blood Orange Polenta Upside Down-Cake with Whipped Crème Fraîche

Ingredients

• 1.5 teaspoons double-acting baking powder 
• 3  blood oranges small to medium unpeeled
• 0.3 teaspoon kosher salt 
• 3 tablespoons cornmeal yellow stone-ground (preferably )
• 1 cup crème fraîche chilled
• 2 large eggs separated
• 2 tablespoons sugar 
• 0.8 cup unbleached all purpose flour 
• 8 tablespoons butter unsalted divided room temperature (1 stick)
• 0.8 teaspoon vanilla extract 
• 3 tablespoons water 
• 6 tablespoons milk whole

Equipment

• bowl
• frying pan
• oven
• knife
• whisk
• blender
• hand mixer
• pastry brush
• oven mitt

Directions

1. Position rack in center of oven andpreheat to 350°F.
2. Combine 6 tablespoonssugar and 3 tablespoons water in 10-inch-diameterovenproof skillet with 8-inch-diameterbottom and 2 1/2-inch-high sides.Stir over medium heat until sugar dissolves.Increase heat and boil without stirring untilsyrup is golden amber (not dark amber),occasionally brushing down sides of skilletwith wet pastry brush and swirling skillet,about 4 minutes.
3. Remove skillet fromheat and whisk 2 tablespoons butter intocaramel. Set aside.
4. Cut off both rounded ends of eachorange so that ends are even and flat. Usingsharp knife, cut oranges into 1/16- to 1/8-inch-thickrounds.
5. Remove and discard anyseeds. Arrange orange slices, overlappingslightly, in concentric circles atop caramel inbottom of skillet.
6. Whisk flour, polenta, baking powder,and coarse kosher salt in medium bowlto blend. Using electric mixer, beat 3/4 cupsugar, remaining 6 tablespoons room-temperaturebutter, and vanilla in anothermedium bowl until light and fluffy.
7. Add eggyolks 1 at a time, beating well after eachaddition.
8. Add flour mixture in 3 additionsalternately with milk in 2 additions, beatingbatter just until incorporated.
9. Using clean dry beaters, beat eggwhites in large bowl until soft peaks form.
10. Add remaining 1 tablespoon sugar and beatuntil stiff but not dry. Fold 1/3 of egg whitesinto batter to lighten, then fold in remainingegg whites in 2 additions. Drop batter bylarge spoonfuls atop orange slices in skillet,then spread evenly.
11. Bake cake until tester inserted intocenter comes out clean, about 45 minutes.Cool cake in skillet 10 minutes. Runsmall knife around cake to loosen.
12. Placeplatter atop skillet. Using oven mitts, holdplatter and skillet firmly together andinvert, allowing cake to settle onto platter.Rearrange any orange slices that may havebecome dislodged. Cool cake completely atroom temperature.
13. Usingelectric mixer, beat chilled crème fraîcheand 2 tablespoons sugar in medium bowluntil mixture thickens.
14. Cut cake into wedges and serve withdollop of whipped crème fraîche.
15. * Available at most supermarkets and atspecialty foods stores.
16. Bon Appétit