Preheat your oven to 325F (165C) and line the bottom of an 8” springform pan with parchment paper. Set aside.

In a large bowl using an electric mixer, beat together cream cheese and sugar (pausing once to scrape sides and bottom of the bowl with a spatula) until mixture is creamy, lump-free, and well-combined.

Stir in sour cream and vanilla extract until well-combined.

With mixer on low-speed, add eggs one at a time, stirring until just-combined after each addition. Scrape the sides and bottom of the bowl with a spatula again and ensure batter is uniform and smooth (don’t over-beat after adding the eggs or cheesecake will be prone to cracking and the texture could end up less smooth than desired).

Pour batter into prepared springform pan and transfer to the center rack of 325F (165C) oven. Bake for 35 minutes or until cheesecake is set. The center may jiggle slightly when finished baking, but the surface should be set if lightly touched with your finger. Edges may be beginning to very slightly crack or brown when finished.

Remove cheesecake from oven, allow to cool for ten minutes then carefully run a knife between the cheesecake and the rim of the pan (this loosens the cheesecake from the pan and helps minimize cracking). Note: I don’t remove the cheesecake from the springform pan until I’m ready to assemble.

Let cheesecake sit at room temperature until cool enough to touch, then cover with foil or plastic wrap and refrigerate for at least 4 hours and up to 2 days before assembly.

In a large bowl, whisk together flour, sugars, cocoa powder, baking soda, and salt.

Add melted butter and vegetable oil and stir (by hand or using an electric mixer) until well-combined (batter will be thick).

Add eggs and vanilla extract and stir well.

Stir in buttermilk until well-combined and batter is smooth.

Carefully add very hot water or coffee and stir until thoroughly combined and batter is uniform. Pour batter evenly into prepared pans and bake on 350F (175C) for 35 minutes or until a toothpick inserted in the center comes out clean or with a few moist crumbs.

Allow cakes to cool for 15 minutes then run a knife around the edge of the cake and carefully invert on a cooling rack to cool completely before assembling. Note: If cakes are domed or not even, I recommend leveling with a cake leveler or sharp knife before assembling.

Using an electric mixer or stand mixer, beat together butter and cream cheese until smooth and well-combined.

Stir in vanilla extract and salt.

With mixer on low-speed, gradually add powdered sugar until completely combined.

Divide frosting in half (you can just eyeball it) and add stir cocoa powder into one half of the frosting until combined.

Place your first cake layer on cake platter and cover with a layer of chocolate frosting.

Remove the collar from the springform pan and, if needed, use a sharp knife to level the cheesecake (sometimes the edges rise slightly, use a knife to trim these off).

Gently swirl remaining frosting together then transfer to a large piping bag fitted with a large closed star tip and pipe decorative dollops on top, if desired.

Store cake in the refrigerator until ready to serve.