Cookie Dough Ice Cream Sandwiches

In a large bowl, mix butter with brown and white sugar. Add milk and vanilla and stir to combine. Stir in flour and salt. When fully combined, fold in chocolate chips. Line a large baking sheet pan with parchment, leaving overhang on sides. Press mixture into the pan, evening it out as much as possible with a cutting board or other flat surface. Top with a second piece of parchment. Freeze until firm, 1 hour. Remove cookie dough from pan and place onto a cutting board. Slice the dough down the center. Spread one half with softened vanilla ice cream, then gently place the other half on top. Transfer back to pan. Freeze for 4 more hours, or overnight. Slice into sandwiches and serve immediately.