Place your cookies in a food processor and blend until you have very fine crumbs. You'll need 2 cups of crumbs, so continue to add more until you reach that yield. Every cookie is different, with different sizes so you will never use the same amount of each cookie.
If you're using a cookie with a soft cream center, like the oreo, you will need to scrape out the centers. The cookie crumbs need to be as dry as possible.
Place cookie crumbs in a large bowl.
In a saucepan melt your butter over medium heat. Stir in the evaporated milk and sweetened condensed milk until the mixture is melted together. Start streaming in the milk/butter mixture into your cookie crumbs in small additions. Stirring well after each addition. Cool the cookie butter in the refrigerator.
If you would like it to be more of a dipping consistency...
Once cool, stir in tablespoons of water at a time. Stir vigorously! It may look like the water is causing the mixture to separate, do not panic! Keep mixing until you achieve a super smooth, super sexy consistency. Store in the refrigerator and this deliciousness will last about 2 weeks.