Preheat the oven to 350°F (175°C).

In a bowl, cream together the softened butter, granulated sugar, and brown sugar until light and fluffy.

Add the eggs one at a time, beating well after each addition.

In a separate bowl, mix the flour, baking soda, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing until combined.

Fold in the M&M's and chocolate chips.

Drop rounded tablespoons of dough onto a baking sheet lined with parchment paper.

Bake for 10-12 minutes or until lightly golden.

Allow the cookies to cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.