Preheat oven to 375° F. Line a baking sheet with parchment paper.
In a mixing bowl, cream together butter and brown sugar until light and fluffy. Add the milk and vanilla and stir to combine.
Add the flour, baking soda and salt and stir to combine. Add the cereal and chocolate chips and mix carefully to combine, trying not to break up the cereal too much (some pieces will crack, which is totally okay).
Chill dough for at least one hour.
Use a cookie scoop to scoop 1 or 2 tbsp of dough into balls. Bake 9 minutes, until golden for smaller cookies or 11 minutes for larger cookies, until golden. Remove from the oven.
Let sit a few minutes on the pan before transferring to a wire cooling rack. Store in an airtight container at room temperature up to 5 day.