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1
TO PREPARE TOPPING: Coat a 10-inch ovenproof skillet (such as castiron) with cooking spray.
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2
Add corn syrup and butter; heat over low heat until butter has melted, swirling the pan to coat the bottom evenly.
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3
Remove from the heat; spread the brown sugar evenly over the bottom of the pan.
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4
Sprinkle the nuts over the sugar and arrange the rhubarb, rounded side down, in a circular pattern on top.
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5
Set aside.
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6
TO PREPARE CAKE: Preheat oven to 375F Combine flour nuts, baking powder and salt in a food processor or blender; process until finely ground.
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7
Beat two egg whites in large bowl with an electric mixer on high speed until soft peaks form.
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8
Gradually add 1/3 cup brown sugar, beating until stiff and glossy.
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9
Set aside.
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10
(It is not necessary to wash beaters).
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11
Beat whole eggs with the remaining 1/3 cup brown sugar in another large bowl on high speed until thickened and pale, 3-5 minutes.
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12
Blend in orange zest and vanilla.
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13
Whisk one-fourth of the beaten whites into the whole egg mixture.
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14
Gently fold in half the flour mixture.
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15
Fold in the remaining beaten whites, followed by the remaining flour mixture.
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16
Spread the batter evenly over the rhubarb.
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17
Bake the cake until the top springs back when touched lightly, 25-30 minutes.
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18
Let cool in the pan on a wire rack for 5 minutes.
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19
Loosen the edges with a knife.
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20
Invert a serving platter over the cake.
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21
Using oven mitts, grasp platter and skillet together and carefully flip them over.
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22
Let the skillet sit for a few minutes to allow any caramel clinging to it drip onto the cake.
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23
Remove the skillet.
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24
Let the cake cool at least 20 minutes.
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25
Serve warm or at room temperature.
