Preheat your oven to 325°F (160°C). Line a 24-cup mini muffin tin with paper liners or silicone cups.

Crush the Oreos in a food processor until fine or put cookies in a zip-top bag and bash them with a rolling pin. Mix the crumbs with melted butter until they hold together when pressed.

Spoon about 1 teaspoon of crumb mixture into each mini cup. Press it down firmly with the bottom of a shot glass or the back of a spoon.

In a large bowl, beat the room-temperature cream cheese until smooth and fluffy.

Add the sugar and mix until combined. Beat in the eggs one at a time, scraping the bowl between additions. Mix in sour cream and vanilla.

Sift in the cocoa powder or fold in melted chocolate, and stir in mini chocolate chips if desired.

Spoon about 1 to 1 1/2 teaspoons of filling over each crust—the cups should be nearly full but not overflowing.

Place the pan on a baking sheet and bake for 15–18 minutes, until the edges are set and the centers still have a slight jiggle.

Let the bites cool at room temperature for about 30 minutes, then transfer to the fridge to chill for at least 1–2 hours.

Top with whipped cream, extra chocolate chips, or a drizzle of melted chocolate. Serve straight from the tray or on a platter.