In a large bowl, beat melted butter, brown sugar, and granulated sugar until smooth and pale. Stir in flour, milk, vanilla, and salt and stir until combined. Fold in chocolate chips.
Invert a 12-cup muffin pan and cover the bottom with plastic wrap.
Press about 1/4 cup of cookie dough around each inverted muffin pan cup to create a bowl. (Depending on how thick you make each bowl, you may only have enough dough for 9 or 10 cups.)
Place the whole pan in the freezer and freeze until solid, about 4 hours.
Scoop ice cream into bowls, drizzle with chocolate sauce and serve immediately.