Add in whole wheat flour and all purpose flour and mix slowly to combine.
Fold in M&Ms and pretzels.
Scoop tablespoons onto a cookie sheet. Leave a lot of room between cookies. They will spread like crazy.
Bake at 350 degrees for 8-12 minutes or until the bottoms are just starting to turn brown. My family prefers cookies on the gooier side, so I tend to try and err on the side of caution by pulling them out a bit early. However, if you like crunchy cookies, leave them in.