Heat the heavy cream in a small saucepan over medium heat until it simmers. Remove from heat and stir in the chocolate chips and vanilla extract until smooth. Let cool to room temperature, then refrigerate for 60 minutes.

Scoop the cooled chocolate mixture into 1-inch balls and roll in crushed graham crackers. Place on a parchment-lined baking sheet and refrigerate for 30 minutes.

Melt the chocolate in a microwave-safe bowl in 30-second intervals, stirring until smooth. Dip each truffle in the melted chocolate, allowing excess to drip off.

Roll the coated truffles in cocoa powder and place back on the baking sheet. Refrigerate for 15-20 minutes to set.