Magic Chocolate Flan Cake

It's worth using good-quality caramel sauce, such as Fat Toad Farm Goat's Milk Caramel. If your blender doesn't hold two quarts, process the flan in two batches. The cake needs to chill for at least eight hours before you can unmold it.

CAKE
1/2 cup caramel sauce or topping
1/2 cup plus 2 tablespoons all-purpose flour
1/3 cup cocoa
1/2 teaspoon baking soda
1/8 teaspoon salt
4 ounces bittersweet chocolate, chopped
6 tablespoons unsalted butter
1/2 cup buttermilk
1/2 cup sugar
2 large eggs
1 teaspoon vanilla extract

FLAN
2 (14-ounce) cans sweetened condensed milk
2 1/2 cups whole milk
6 ounces cream cheese
6 large eggs plus 4 large yolks
1 teaspoon vanilla extract

FOR THE CAKE: Adjust oven rack to middle position and heat oven to 350 degrees. Grease 12-cup nonstick Bundt pan. Microwave caramel until easily pourable, about 30 seconds. Pour into pan to coat bottom. Combine flour, cocoa, baking soda, and salt in bowl; set aside. Combine chocolate and butter in large bowl and microwave at 50 percent power, stirring occasionally, until melted, 2 to 4 minutes. Whisk buttermilk, sugar, eggs, and vanilla into chocolate mixture until incorporated. Stir in flour mixture until just combined. Pour batter over caramel in prepared pan.

FOR THE FLAN: Process all ingredients in blender until smooth, about 1 minute. Gently pour flan over cake batter in Bundt pan and place pan in large roasting pan. Place roasting pan on oven rack and pour warm water into roasting pan until it reaches halfway up the side of the Bundt pan. Bake until toothpick inserted in cake comes out clean and flan registers 180 degrees, 75 to 90 minutes. Transfer Bundt pan to wire rack. Let cool to room temperature, about 2 hours, then refrigerate until set, at least 8 hours. (Remove roasting pan from oven once water has cooled.)

Place bottom third of Bundt pan in bowl of hot tap water for 1 minute. Invert completely flat cake platter, place platter over top of Bundt pan, and gently turn platter and pan upside down. Slowly remove pan, allowing caramel to drizzle over top of cake. Serve.