Preheat oven to 325°F (165°C). Line a 9-inch springform pan with parchment paper, spray with non-stick spray, and wrap tightly in two layers of heavy-duty aluminum foil.
Beat 24 oz softened cream cheese until smooth. Add 1 cup sugar, 3 tbsp flour, and 1/4 tsp salt, mixing until combined. Add sour cream, heavy cream, and vanilla, then add eggs one at a time, mixing just until incorporated.
Pour batter into the springform pan and place in a roasting pan. Fill with hot water halfway up the sides and bake for 55-65 minutes until edges are set but center still jiggles slightly. Turn off oven, crack door, and cool for 1 hour. Refrigerate for at least 6 hours or overnight.
Preheat oven to 350°F (175°C). Grease two 9-inch round cake pans and line with parchment paper. Whisk together flour, cocoa powder, baking soda, and salt.
Beat butter and sugar until light and fluffy. Add oil, then eggs one at a time. Mix in vanilla and red food coloring. Stir buttermilk and vinegar together. Alternately add dry ingredients and buttermilk mixture, starting and ending with flour.
Divide batter between prepared pans and bake for 28-33 minutes until a toothpick comes out clean. Cool in pans for 15 minutes, then turn out onto a wire rack to cool completely.
Beat 16 oz cream cheese until smooth. Add butter and beat until light and fluffy. Gradually add sifted powdered sugar, then vanilla and salt. Add heavy cream as needed for spreadable consistency.
Level the cooled red velvet cake layers by trimming any domed tops with a serrated knife. Reserve cake trimmings for garnish.
Release the cheesecake from the springform pan. Place one leveled red velvet layer on a serving plate. Spread with 1/2 cup of frosting. Place the cheesecake on top, then spread with another 1/2 cup of frosting. Top with the second red velvet layer, cut-side down.
Apply a thin crumb coat all over the cake and refrigerate for 20-30 minutes. Finish with the remaining frosting, smoothing the top and sides. Garnish with crumbled cake trimmings if desired. Refrigerate for at least 1 hour before slicing.