Prepare a 9" spring form pan (or a cake pan with removable bottom), line parchment paper on the bottom, and spray it with oil.
With an electric mixer, beat cream cheese until smooth. Add sugar and mix for 3-4 minutes, until combined. Scrape gown the sides of bowl, to make sure all cream cheese is incorporated. Then add sour cream, heavy cream and vanilla. Mix until combined. Add eggs, one at a time, beat until incorporated. Pour batter into the cheesecake pan.
Place pan on the upper rack of the oven and bake for 45 minutes at 325 F, until the top is set. Transfer cheesecake to a cooling rack and let it cool down completely, without opening the sides of the springform. When completely cool, freeze for at least 2 hours or overnight. The frozen cheesecake layer is easier to use when assembling the cake.
Prepare 2 9" cake pans and spray them with baking spray. In a large bowl combine all dry ingredients: flour, sugar, salt, cocoa powder and baking soda and give mixture a stir.
Add eggs, buttermilk, oil and food coloring and mix for 2-3 minutes on medium speed until blended. Scrape the sides of the bowl with a spatula if needed. Spread batter into cake pans, dividing the amount equally. Bake for 35 minutes, until toothpick inserted comes out clean. Take out of the oven and let them cool for 15 minutes. Remove cake layers from pans and set on a cooling rack to cool down completely.
If cheesecake layer is slightly larger, shave off some of the sides of it to make them the same size.
Add the other cake layer on top. Using a long and thin spatula apply a thin coat of frosting to the cake. Make sure you wipe off cake crumbs of the spatula, so they don't transfer to the bowl of icing. Refrigerate for 30 minutes.
Then add a second, thicker layer of cream cheese frosting to the cake, spreading it evenly. Decorate cake with a piping bag , fresh berries or some chocolate shavings. I used to decorate mine with white chocolate shavings. Now I only added strawberries. Keep cake in the fridge.