Preheat your oven to 350°F (175°C). In a bowl, combine crushed chocolate cookies with melted unsalted butter until resembling wet sand. Line a muffin tin with cupcake liners and press the mixture firmly into each liner. Bake for 10 minutes, then cool.

Beat softened cream cheese and granulated sugar together using an electric mixer for about 2 minutes. Add sour cream or yogurt, cocoa powder, and mix well. Fold in melted chocolate chips.

Spoon the filling into the cooled crusts, filling each liner just below the top. Bake for approximately 20 minutes until set around the edges but slightly jiggly in the center. Cool in oven with door ajar for 15 minutes.

Let the cheesecakes cool at room temperature for 30 minutes, then refrigerate for at least 2 hours.

To prepare the ganache, heat 1 cup of heavy cream until simmering. Pour over 1 ½ cups chocolate chips, stir until smooth. Whip remaining heavy cream until soft peaks form and fold in cocoa powder and sugar.

Carefully remove cheesecakes from the muffin tin. Top with ganache and a dollop of whipped cream before serving chilled.