Preheat oven to 350°F (175°C).
In a large bowl, cream together the butter, granulated sugar, and brown sugar until smooth.
Beat in the vanilla extract, milk, and eggs, then gradually blend in the dry ingredients.
Stir in the chocolate chips and M&Ms by hand using a wooden spoon.
Drop cookie dough by rounded tablespoonfuls onto ungreased baking sheets.
Bake for 8 to 10 minutes in the preheated oven, or until edges are nicely browned.
Allow cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.