Preheat oven to 325 degrees F.

In a stand mixer, combine the cream cheese, eggs, vanilla, salt, food coloring, and sweetener. Blend on medium speed until smooth. Add cocoa powder and sour cream, blend on high speed until smooth.

Grease or line a 4-inch springform pan with parchment paper. Wrap the bottom of the pan with aluminum foil, place it into an 8-by-8-inch baking dish. Pour hot water into the dish until halfway up the sides of the pan.

Pour the cheesecake filling into the springform pan and bake for 40-45 minutes. Check at 35 minutes and continue until center is set.

Remove from oven, let cool for 10 minutes. Remove from water bath, refrigerate for 4-6 hours or overnight.

When ready to serve, melt chocolate chips and butter together, mix until smooth. Drizzle over cheesecake if desired.