1to 1 1/2 4 oz bars of real white chocolate (not candy coating)
To Make the Cake
Preheat oven to 350F. Spray 2 9” cake pans with pan spray. Line the bottoms with rounds of parchment and
spray again. Set aside.
In a large bowl, combine the cake mix, water, sour cream, mayonnaise, eggs, and yolk, salt, and vanilla. Using a hand mixer, mix on low speed for about 30 seconds. Scrape the bowl. Increase speed to medium and beat for 2 minutes. Divide the batter evenly between the two pans and bake in the center of the oven for 22-25 minutes, or until the tops spring back when lightly pressed, and the cakes are just starting to pull away from the sides of the pan. Allow to cool in pans for 15 minutes and then invert onto cooling racks. Invert again, so cakes cool right-side up. Note, the cakes will dome quite a bit. Once cool, use a large serrated knife to slice off the entire cake dome as evenly as you can. You should have two even discs of cake approximately 3⁄4” thick. Wrap well and refrigerate.
For the Cheesecake Place racks in the upper and lower thirds of the oven. Put a rimmed baking sheet on each rack. Preheat the oven to 300F. Spray 2 9” cake pans with pan spray. Line the bottoms with rounds of parchment and spray again. Don’t skip the parchment, because you’ll be turning these out once chilled.
Set aside. Bring 2 quarts of water to a boil. Put the cream cheese in a large bowl. Using a hand mixer, beat on medium-low speed until smooth. Add sugar, vanilla, and salt, and continue to beat until well combined and smooth. Scrape the bowl as necessary. Add the eggs, one at a time, beating well after each addition and scraping the bowl as needed. Whisk the cream and flour together, so there are no lumps. Beat this mixture evenly into the rest. Pour half of the batter into each prepared pan and smooth the tops. Pull out the top rack, place one of the cheesecakes into the rimmed baking sheet and then pour in boiling water to come up to the level of the batter, about 3⁄4”. Carefully slide the rack back in. Repeat with the other pan on the lower rack. Bake 20 minutes. Carefully rotate each pan and then continue to bake an additional 10 minutes.
Turn the heat off, open the oven door for a few seconds to let some heat escape, and then close the oven door. Allow cakes to remain in the cooling oven an additional 30 minutes. Crack oven door open and let sit for 30 more minutes. Remove to racks and run a thin spatula around the inside of each pan to make sure the cakes have released from the sides. Cool completely, and then chill in the refrigerator for at least 4 hours or overnight. When cooled, turn cheesecakes out onto parchment-lined lined racks. Place lined rack on top of the pan, invert both and give a firm rap on the counter. The cheesecake should release from the pan with no problem. If you do have issues, set the bottom of the pan in warm water for 15 seconds and try again. Freeze the cheesecakes and then wrap well. Leave in the freezer until ready to assemble.
Cream Cheese Frosting
For the Cream Cheese Frosting In a large bowl, use a hand mixer to beat the cream cheese and butter together until smooth. Add the salt and vanilla and continue to beat until smooth and creamy. Slowly beat in the powdered sugar, scraping the bowl as necessary. Beat in the cream, a bit at a time, until you have a nice spreading consistency.
To Assemble and Decorate It is easiest to assemble the cake on the stand or platter you’ll be serving it on, so make sure it is a good 12” in diameter and is nice and flat. Using a vegetable peeler, shave the sides of the bars of white chocolate to make curls. Catch them on a piece of parchment or a plate and refrigerate until needed. Place a tablespoon of frosting in the center of your platter and then press one of the cake rounds down into it, making sure to center the cake. Spread 3⁄4 cup of frosting evenly over the cake layer. Place one of the frozen cheesecake rounds onto the frosting and press down lightly. Frost with an additional 3⁄4 cup of frosting. Place the other cake round on top of the frosting and press down gently. Top with another 3⁄4 cup of frosting and then finish with the last frozen round of cheesecake. Scrape the rest of the frosting out onto the top of the cake. Spread it out into an even layer and then spread the excess that extends over the edge of the cake thinly around the sides. Use an offset spatula to make a simple zigzag design in the frosting on the top of the cake. Press the white chocolate curls liberally around the sides of the cake. Leave in the refrigerator for at least 4 hours before slicing and serving with a signature tall swirl of whipped cream.