In a medium-size bowl, whisk together flour and baking soda. Set aside.
In a large bowl using an electric mixer, beat together butter and sugars on medium speed until light and fluffy. Add eggs and vanilla extract; mix until combined.
Scrape down the sides of the bowl, add cocoa powder and pudding mix; mix on low speed until combined. Add flour mixture; mix on low speed until combined.
Scoop dough into heaping tablespoon rounds, or use a #50 disher to scoop balls of dough. Press a couple of remaining M&M's Chocolate Candies into the tops of the dough balls.
Place balls of dough on a tray or baking sheet, cover with plastic wrap, and refrigerate for at least 2 hours. Do not bake cookies without chilling as they are prone to spreading.
Bake 10-12 minutes or until edges have set. Do not overbake, which is easy to do with chocolate cookies.
Cool cookies on a baking sheet on a wire rack for 5 minutes; transfer to a wire rack to cool completely. Eat & Enjoy!
Notes
Halloween Chocolate M&M Cookies should be stored in an airtight container and will keep for 4+ days.¹ You want a 3.7-3.9 ounce package of instant pudding mix NOT sugar-free or cook & serve. You're also NOT making the pudding, just using the dry mix in the batter.