Preheat oven to 350 degrees F. Line 9 x 9 or 8 x 8 pan with parchment paper.
Crush the Oreos in a food processor or in a plastic bag until finely crushed. In a small bowl, add melted butter, and stir until well combined. Press Oreo crust evenly into bottom of the pan making sure to go all the way to the edges.
Melt chocolate in a double boiler or in the microwave. In the microwave, it takes about 1 minute 20 seconds. Stir gently until smooth, returning to the microwave in 15 second increments, if needed.
In a stand mixer or mixing bowl, beat cream cheese and sugar and coco powder until smooth and creamy. There should be no lumps or the cream cheese wasn't room temperature. Add vanilla extract, cream, and eggs, Beat until smooth. Stir in melted chocolate until smooth.
Pour and spread into the baking pan evenly.
Bake for 35-43 minutes until just set. It should look cooked but still be a little jiggly. After pulling out of the oven, run a knife around the outside to keep the top from cracking.
Allow to cool, transfer to fridge at least 6 hours, then slice and serve. Top with whip cream or chocolate shavings if desired.