Preheat the oven to 350 F.

In a large bowl combine butter and sugars. Beat on low with an electric hand mixer or in a bowl of a stand mixer until smooth and creamy. Add egg, vanilla. Mix on low until combined. Set aside.

In a separate large bowl, combine dry ingredients. Whisk to combine and add to wet ingredients gradually. Add ½ or 1 cup at a time, beat on low until combined, and then continue with the next batch.

Mix until ingredients are almost combined, a few lumps here and there are fine.

Stir in M&Ms. The batter will be thick, a little sticky and I recommend refrigerating it. Freeze for 30 minutes to 1 hour in the fridge. It is important to chill the batter between the batches too (simply for the sake of all uniform cookies).

The batter will resemble playdough and should not be sticky after chilling. You should be able to roll small balls easily. If it is too frozen at this point, wait at room temp until it’s softened slightly. Scoop 2 tablespoonfuls of batter, rolling it into about 2 inch balls. (Should be around 13-14 cookies)

Arrange the cookie balls on a baking sheet lined with parchment paper at least 2 inches apart. Don’t press down!

Bake for 10-12 minutes (the time varies due to different ovens).

The cookies will have a soft center inside. Once they cool down they will set well and the texture inside remains soft, chewy and buttery.

Let the cookies stand in the pan for 5-10 minutes before transferring to a wire rack to cool completely.