Preheat oven to 300°F (148°C). Line a 9-inch springform pan with parchment paper, spray with non-stick spray, and wrap the outside tightly with two layers of aluminum foil.
Beat cream cheese until smooth (2-3 minutes), then add sugar and flour, beating for 2 minutes. Add eggs one at a time on low speed, then mix in sour cream, heavy cream, and vanilla until just combined.
Pour batter into prepared pan, tap to release air bubbles, then place in a roasting pan. Add hot water to come 1 inch up the sides and bake for 55-65 minutes until edges are set but center jiggles slightly.
Turn off oven, crack door open 4 inches, and let cheesecake cool in oven for 1 hour. Remove from water bath, cool completely at room temperature for 1 hour, then wrap tightly and freeze for at least 3 hours or overnight.
Preheat oven to 350°F (175°C). Grease two 9-inch round cake pans, line with parchment, grease parchment, and dust with flour.
Whisk together flour, cocoa powder, baking soda, and salt in a medium bowl. In a large bowl, beat oil and sugar for 2 minutes, then add eggs one at a time, beating well after each.
Whisk together buttermilk, red food coloring, vinegar, and vanilla. Alternately add flour mixture and buttermilk mixture to oil mixture, beginning and ending with flour, mixing just until combined.
Divide batter evenly between prepared pans and bake for 28-32 minutes, rotating pans halfway through, until a toothpick comes out with moist crumbs. Cool in pans for 15 minutes, then invert onto wire racks to cool completely (about 1 hour).
Beat cream cheese and butter together for 3-4 minutes until smooth and fluffy. Gradually add powdered sugar one cup at a time, then add vanilla and 2 tablespoons heavy cream, beating on medium-high for 2-3 minutes until light and fluffy.
Remove frozen cheesecake from springform pan and peel away parchment. Level the tops of both red velvet layers with a serrated knife.
Place first red velvet layer cut-side up on serving plate. Spread 1/2 cup frosting on top, place frozen cheesecake layer on top, spread another 1/2 cup frosting, then top with second red velvet layer cut-side down.
Apply a thin crumb coat of frosting over entire cake and refrigerate for 30 minutes. Apply final layer of frosting smoothly over cake, creating desired finish with offset spatula.
Refrigerate assembled cake for at least 2 hours before slicing to allow cheesecake to thaw slightly and layers to set. For clean slices, use a hot knife wiped clean between cuts.