Place chocolate chips and butter in a large bowl. Heat heavy whipping cream in the microwave or in a double broiler until boiling. Pour over chocolate chips. Let sit for 3 minutes, then whisk until smooth.
Add vanilla extract and salt to the chocolate mixture and mix to combine. Grind cookies to cookie crumbs in a food processor or crush them in a bag. Combine the crumbs with the chocolate mixture. Cover and chill mixture in the refrigerator for 20 minutes.
Roll truffle mixture into 1 inch balls. Wet your hands if you find that they are too sticky to roll. Roll in coating (cocoa powder, sprinkles, or coloured sugar). Chill in the refrigerator for 1 hour before serving.
To make coloured sugar, pour sugar into a resealable bag. Add drops of food colouring and seal up the bag. Using your hands, knead gently until colour is evenly distributed.
Notes
If whipping cream is not melting the chocolate fully, put the whole bowl in the microwave and heat slowly until chocolate is melted.
Use semi-sweet chocolate chips for best taste. Milk chocolate would be too sweet.
Use whichever kind of coating you like (cocoa powder, sanding sugar, sprinkles, toasted nuts, or colour your own sugar).