Melt chocolate either in a double boiler or in the microwave. To melt in the microwave, place in a micro-wave safe bowl and heat on high for 30 seconds. Stir well and return to microwave for another 30 seconds. Remove, stir again and if not completely melted return to microwave for 10 seconds at a time, stirring after each 10 seconds until completely melted. Set aside to cool.
With an electric mixer, beat cold butter for two minutes. Scrape down sides of bowl and add sugar. Beat for 5 minutes, stopping several times to scrape sides of bowl.
Add cooled, melted chocolate and beat again for two minutes, stopping occasionally to scrape down sides of mixing bowl.
Add eggs one at a time, beating for 2 minutes after each addition. If you are using eggs that you've pasteurized yourself, add the yolks first and beat well for a minute, then add ⅓ of the whites at a time, beating for 2 minutes after each addition. Thorough beating at high speed is essential. If it looks curdled don't give up.
Fold in crushed peppermints and crushed chocolate water cookies. Spoon or pipe into small bowls or cups. Freeze for at least an hour. Once frozen, cover and store in an airtight container. Remove from freezer about 10 minutes before serving or transfer to refrigerator an hour before serving.