In a large mixing bowl, whisk together melted butter with brown sugar and granulated sugar. Whisk in milk, vanilla extract, and salt. Use a rubber spatula to stir in flour until thoroughly combined. Then stir in chocolate chips.
Transfer cookie dough to the prepared baking sheet and flatten until 1/4 inch thick. Use another baking sheet to press it down into an even layer of needed.
Freeze cookie dough on baking sheet, 1 hour, until frozen.
Remove frozen cookie dough sheet from pan and slice in half.
Scoop vanilla ice cream onto one half of the cookie dough into a thick, even layer. Top with remaining cookie dough sheet.
Freeze 4 hours until firm.
Cut into individual servings and serve immediately or package in a resealable plastic bag for longer term frozen storage.