In a medium mixing bowl, beat together the brown sugar, butter, eggs and vanilla until they are thoroughly combined.

Gradually add in the the flour, then your baking powder and salt, beating lightly until combined.

Stir in chocolate chips and M&M's - do not beat them into the mixture, as you want them to be whole!

Pour your batter into your greased baking dish and bake at 350 degrees for 18-20 minutes or until a toothpick inserted near the center comes out clean.

Cool on a wire rack and then put into the refrigerator for about half an hour.