Instructions

• Remove from the refrigerator the cream cheeses (both packages for the cheesecake and the 6-ounce block for the frosting), eggs (for both cheesecake and cake), and the butter (for the cake and frosting) so they come to room temperature while you preheat the oven.
• Preheat the oven to 325°F. Place a 13x9-inch pan half-full of hot water on the lower third rack of the oven. Place an empty rack directly above that pan. Spray a 9-inch springform pan with nonstick spray.
• Make the cheesecake filling: In a large bowl, beat the two 8-ounce packages of cream cheese with an electric mixer on medium speed until smooth and creamy, about 1–2 minutes. Add 2/3 cup granulated sugar and a pinch of salt; blend 2 minutes, scraping down the sides of the bowl as needed.
• Add the 2 large eggs one at a time, beating after each addition until incorporated. Mix in 1/3 cup sour cream, 1/3 cup heavy whipping cream, and 1 teaspoon vanilla extract. Beat until the mixture is smooth and homogenous.
• Pour the cheesecake batter into the prepared 9-inch springform pan. Place the springform pan on the oven rack above the roasting pan of water. Bake at 325°F for 40–45 minutes, until the cheesecake is set to the touch and not jiggly in the center.
• Remove the cheesecake from the oven and let it cool on a wire rack for at least 1 hour. After it has cooled, place the cheesecake (still in the springform pan) in the freezer and freeze until completely firm, about 4–5 hours or overnight.
• While the cheesecake chills, prepare the cake layers: Preheat the oven to 350°F. Spray two 9-inch round cake pans with baking spray that contains flour (or spray and lightly flour them).
• In a large bowl, whisk together 2 cups all-purpose flour, 2 cups granulated sugar, 2 teaspoons baking powder, and 1 teaspoon salt. Add 3 large eggs, 1 cup buttermilk, 1/2 cup (1 stick) unsalted butter (room temperature), 1/2 cup shortening, 2 teaspoons finely grated lemon zest, and 1/4 cup freshly squeezed lemon juice.
• Use an electric mixer on low speed to combine the cake ingredients for 1 minute. Scrape the sides and bottom of the bowl, then beat on high speed for 2 minutes. Add 1/4 cup lemon-lime soda (Sprite or 7-Up) and 1 teaspoon vanilla extract; beat on low speed for 30 seconds to incorporate.
• Divide the batter evenly between the two prepared 9-inch pans. Bake at 350°F for 25–30 minutes, or until a toothpick inserted into the centers comes out with just a few moist crumbs attached. Let the pans cool on a wire rack for about 20 minutes, then run a knife around the edges and invert the layers onto the rack to cool completely.
• Make the lemon cream cheese frosting: In a large bowl, beat 6 ounces cream cheese and 1 cup (2 sticks) unsalted butter on high speed until creamy. Gradually add 4 1/2 cups powdered sugar, beating on low speed until blended, scraping down the bowl as needed. Add 1 tablespoon finely grated lemon zest and 1/4 cup freshly squeezed lemon juice; beat on high speed 1–2 minutes until fluffy. If the frosting is too thick, add an additional tablespoon or two of lemon juice (as needed) to reach a spreadable consistency. Cover and refrigerate the frosting until assembly (it will firm up slightly).
• Assemble the cake: Place one cooled 9-inch cake layer on a cake plate or platter. Spread a few spoonfuls of frosting on the cake layer to act as glue.
• Remove the frozen cheesecake from the freezer. Release and remove the sides of the springform pan. If the cheesecake is larger than the cake layers, trim the cheesecake to match the 9-inch diameter of the cake layers and level the top if needed. Slide the cheesecake disk onto the frosted first cake layer. Spread a few teaspoons of frosting on top of the cheesecake to help it adhere.
• Place the second cake layer on top of the cheesecake. Use the remaining frosting to cover the top and sides of the cake, smoothing as desired. Refrigerate the assembled cake until serving. The cake can be made and refrigerated up to 24 hours in advance. Keep refrigerated until ready to serve.