Preheat the oven to 350°F (175°C). Grease and line two 8-inch round pans with parchment paper. Whisk flour, cocoa powder, baking soda, and salt in one bowl. In another bowl, mix buttermilk, vinegar, vanilla, and red gel coloring until evenly combined.

Cream butter and sugar for about 3 minutes until light and fluffy, then add eggs one at a time, mixing well after each addition. Alternate adding the dry ingredients and the buttermilk mixture, starting and ending with dry.

Divide the batter evenly between pans and bake for 22 to 25 minutes, until the tops spring back lightly when touched. Cool completely before assembling. Slight sinking in the center is normal.

Lower the oven temperature to 325°F (160°C). Wrap the outside of an 8-inch springform pan tightly with foil. Beat cream cheese and sugar until smooth, then mix in vanilla. Add eggs one at a time, followed by sour cream and heavy cream, mixing just until combined.

Pour the batter into the pan, place it in a roasting pan, and add hot water halfway up the sides. Bake for 55 to 65 minutes, until the edges are set and the center still jiggles slightly. Cool completely, then refrigerate for at least 4 hours or overnight.

Combine strawberries, sugar, cornstarch, lemon juice, and water in a saucepan. Simmer over medium heat for 8 to 10 minutes, stirring often, until thick and glossy. Remove from heat and let cool fully. The topping will continue to thicken as it cools.

Place one red velvet cake layer on a serving plate. Remove the cheesecake from the pan and center it on top. Add the second red velvet layer, then spoon the cooled strawberry topping over the cake, letting it drip naturally down the sides.

Beat cream cheese, butter, vanilla, and powdered sugar until smooth. Pipe or spread the frosting around the edges and finish with fresh strawberries if desired.