In a large bowl, mix butter and sugars together for 2-3 minutes. Add eggs and vanilla and blend for another 2 minutes.
In a separate bowl, mix together the flour, cinnamon, baking soda, baking powder and salt until well combined.
Add the flour mixture to the butter mixture and mix just until combined. Add the oats, half of the M&Ms and chocolate chips and stir until evenly distributed throughout the dough.
Place the other half of the M&Ms into a small bowl. Use a cookie scoop to scoop the dough into balls and then press the top of each cookie dough ball into the M&Ms, so that each cookie dough ball is well coated with M&Ms on the top.
Place cookie dough balls onto a well-greased cookie sheet or a cookie sheet that has been lined with parchment paper or a silicone baking mat.
Bake cookies for about 12 minutes or until the edges just barely begin to brown. Don't overbake! Let the cookies cool on the cookie sheet for a few minutes before transferring them to a wire rack to cool completely.