This is a cake that even folks who normally eschew cake will enjoy. It’s not overly sweet, and the addition of polenta adds a bit of crunch to the crumb.
- 7 T. sugar, divided, plus 3/4 c. sugar
- 3 T. water
- 8 T. (1 stick) unsalted butter, room temperature, divided
- 3 unpeeled small to medium blood oranges
- 3/4 c. plus 3 T. unbleached all purpose flour
- 1 1/2 tsp. baking powder
- 3 T. polenta or coarse yellow cornmeal (preferably stone-ground)
- 1/4 tsp. salt
- 3/4 tsp. vanilla extract
- 2 large eggs at room temperature, separated
- 6 T. milk, preferably whole milk, at room temperature
Position rack in center of oven and preheat to 350 degrees F. Combine 6 tablespoons sugar and 3 tablespoons water in a 10-inch diameter ovenproof skillet or cakepan that has at least 2 1/2-inch-high sides. Stir over medium heat until the sugar dissolves. Increase heat and boil without stirring until syrup is golden amber (not dark amber), occasionally swirling the skillet and brushing down sides of the skillet with a wet pastry brush, about 4 minutes. Remove skillet from heat and whisk 2 tablespoons of butter into caramel. Set aside and cool to room temperature.
Cut off both rounded ends of each orange so that ends are even and flat. Using sharp knife, cut oranges into 1/16- to 1/8-inch-thick rounds. Remove and discard any seeds. Arrange orange slices, overlapping slightly, in concentric circles atop caramel in bottom of skillet.
Whisk flour, polenta, baking powder and coarse kosher salt in medium bowl to blend. Using electric mixer, beat 3/4 c. sugar, the remaining 6 T. room-temperature butter, and vanilla in another medium bowl until light and fluffy. Add egg yolks 1 at a time, beating well after each addition. Add flour mixture in 3 additions alternately with milk in 2 additions, beating batter just until incorporated.
Using clean and completely dry beaters, beat egg whites in a large bowl until soft peaks form. Add remaining 1T. sugar and beat the egg whites until they form stiff peaks; being careful to not overbeat to the point that they begin to dry. Fold 1/3 of egg whites into batter to lighten, then fold in remaining egg whites in 2 additions. Drop batter by large spoonfuls atop orange slices in skillet, then gently spread it evenly around the skillet, being careful to not dislodge the orange slices. This is easiest to do with an offset spatula.
Bake the cake until a tester inserted into the center comes out clean, about 45 minutes. Cool the cake in the skillet 10 minutes, then run a small knife around the edges to loosen it. Place a platter that’s at least slightly larger than the skillet over the top. Using hot pads, hold the platter and skillet firmly together and flip them upside down. If the cake doesn’t immediately drop onto the platter, jiggle the skillet and platter gently to loosen it. Remove the skillet and rearrange any orange slices that may have become dislodged. The cake can be served slightly warm or at room temperature. Blood orange polenta cake is wonderful all by itself, but even better with a dollop of slightly sweetened whipped cream or a small scoop of ice cream. Vanilla ice cream pairs well with the cake; as does chocolate, coffee or rum raisin ice cream.