Crush your potato chips and pretzels, then set aside. Add the chocolate chips and sweetened condensed milk to a medium saucepan and cook over medium heat, stirring the entire time.
After the chocolate chips have melted, remove from heat and add vanilla; stir.
Add ½ of the crushed potato chips and ½ of the crushed pretzels. Blend gently.
Pour into an 8x8 greased pan and spread into the bottom.