Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper.
In a large bowl, cream together the butter, granulated sugar, and brown sugar until light and fluffy.
Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
In another bowl, whisk together the flour, baking soda, baking powder, and salt. Gradually add to the creamed mixture, mixing until just combined.
Stir in the chocolate chips and M&M's.
Drop by rounded tablespoon onto prepared baking sheets. Flatten slightly with the back of the spoon.
Bake for 10-12 minutes, or until the edges are lightly browned. The centers may still look soft, but they will set as they cool.
Allow cookies to cool on the baking sheets for 5 minutes before transferring to wire racks to cool completely.