Preheat your oven to 325°F. Line a rimmed baking sheet with unbleached parchment paper and set it aside.
In a large bowl, place the ingredients of the cake mix, and whisk to break up any lumps and combine well.
Add the butter and mix into with the back of a mixing spoon into the dry ingredients until the mixture resembles sand.
Add the beaten eggs, and mix to combine. The dough will be thick, but soft.
Add the M&Ms, and mix until they are evenly distributed throughout, handling as little as possible so the colors don’t run.
Drop the dough by rounded tablespoon on the prepared baking sheet (a #50 cookie scoop works perfectly), 2 inches apart.
With wet fingers, press each piece of cookie dough into a 1/2-inch thick disk.
Place the cookies in the center of the oven and bake until lightly browned on the underside and edges, about 9 minutes.
Allow to cool until set on the baking sheet until firm. They will flatten as they cool.
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Notes
For the cake mixYou can use any 16-ounce box of gluten free yellow cake mix, if you don't want to make your own. Please note that most gluten free cake mixes on the market tend to be gritty, so for the best results, make your own gf cake mix.For the M&MsMost varieties (including plain and mini) of M&Ms are gluten free in the U.S.You can also use an equal amount, by weight:
Gluten free sprinkles (Cake Mate brand is gluten free)
Gluten free edible confetti (Americolor brand is gluten free)
If you use anything other than the mini M&Ms, the cookies will spread less so consider pressing the portions of cookie dough down into thinner disks.Nutritional informationIt is calculated as a courtesy using an online nutrition calculator, assuming candy-coated chocolate pieces like M&Ms. It is only an estimate and should not be relied upon.