Preheat oven to 375ºF.
Start by mixing together sugars, butter, vanilla and egg in large bowl.
In a separate bowl, stir together flour, baking soda and salt. Once combined, mix into cookie mixture about 1/2 cup at a time. Stir in chocolate chips and M&Ms.
Place rounded, heaping tablespoonfuls about 2 inches apart onto a cookie sheet.
Bake 7 to 10 minutes or until edges are light brown. Centers will be soft. Let cookies cool for 5 minutes before moving them to a cookie rack to completely cool.