Cornmeal Cake Trifle with Sabayon and Candied Kumquats

Bring kumquats and 1 cup water to a boil in a small saucepan over medium-high. Drain and discard liquid; set kumquats aside. Add sugar and remaining 1/2 cup water to saucepan; bring to a boil over medium-high. Cook, stirring occasionally, until sugar dissolves, about 1 minute. Add kumquats; reduce heat to medium-low, and cook, stirring occasionally, until kumquats appear translucent, 4 to 6 minutes. Drain well (reserve drained kumquat syrup for another use).

Remove peels and white pith from oranges using a sharp knife. Working over a bowl, cut between the orange membranes to release fruit segments into bowl. Squeeze membranes over bowl to yield about 1/2 cup juice. Using a slotted spoon, remove orange segments from bowl, and set aside. Add sugar, lemon juice, and salt to orange juice in bowl; whisk until sugar is dissolved, 1 to 2 minutes. Return orange segments to bowl; toss to coat. Cover and chill at least 2 hours or up to 2 days. Drain oranges (reserve liquid for another use).

Preheat oven to 350°F. Coat a 9-inch round cake pan with cooking spray; line with parchment paper, and lightly coat parchment with cooking spray. Set aside. Whisk together flour, sugar, cornmeal, baking powder, and salt in a medium bowl. Whisk together eggs, buttermilk, lemon zest and juice, blood orange zest, and vanilla in a separate medium bowl. Make a well in middle of flour mixture; pour in buttermilk mixture, followed by melted butter. Whisk until evenly incorporated and smooth, being careful not to overmix.

Transfer batter to prepared cake pan; spread in an even layer. Bake in preheated oven until cake is slightly golden and a wooden pick inserted in center comes out clean, 24 to 28 minutes. Transfer cake in pan to a wire rack; let cool 10 minutes. Run a knife around inside edge of pan, and invert cake onto wire rack. Let cool completely, about 1 hour. 

Fill a large bowl with ice water; set aside. Fill a medium saucepan with water to a depth of 1 inch; bring to a simmer over medium-low. Meanwhile, place heavy cream in a large bowl; whisk vigorously by hand until stiff peaks form, 1 to 2 minutes. Refrigerate until ready to use, up to 1 hour. Whisk together egg yolks, sugar, and salt in a large heatproof bowl until well combined. Add Prosecco, and whisk well to combine. Set bowl over simmering water in saucepan, ensuring bottom of bowl doesn’t touch water; cook over medium-low, whisking constantly, until mixture is very thick and glossy and triples in volume, 5 to 8 minutes. Remove from heat, and set bowl in prepared ice water–filled bowl; whisk constantly until cold, about 5 minutes. Fold in whipped cream. Cover and refrigerate up to 2 hours.

Combine sugar, 1/3 cup water, and salt in a small saucepan, and cook over medium-high, stirring often, until sugar is dissolved and mixture registers 240°F on an instant-read thermometer, 6 to 8 minutes. When sugar mixture is almost up to temperature (about 225°F), beat egg whites in bowl of a stand mixer fitted with the whisk attachment on medium speed until foamy, about 30 seconds. Add cream of tartar, and beat on medium speed until soft peaks form, 1 to 2 minutes. (The sugar mixture should reach 240°F at the same time the egg whites reach soft peaks.) With mixer running on medium speed, gradually drizzle in sugar mixture. Increase mixer speed to medium-high, and beat until mixture is glossy and stiff peaks form, 1 minute and 30 seconds to 2 minutes. Set aside.

Spoon one-third of the sabayon (about 1 cup) in an even layer in a 31/2-quart trifle dish. Using a serrated knife, cut cake in half horizontally to create 2 even layers. If needed, trim cake layers to fit trifle dish. Place 1 cake layer on top of sabayon in trifle dish. Top with half of the marinated oranges (about 1 cup) and half of the candied kumquats (about 1/4 cup). Repeat layers once with one-third of the sabayon, the second cake layer, remaining marinated oranges, and remaining kumquats, layering ingredients all the way to edge of trifle dish. Top with remaining sabayon in an even layer. Top trifle with meringue; toast using a kitchen torch. Serve immediately, or chill, uncovered, up to 12 hours.