In a large bowl using an electric mixer, beat together butter, egg, and vanilla on high speed until combined. It is OK if it is not completely combined, it will come together more with the dry ingredients.
Add all jar ingredients to wet ingredients; mix on low speed until combined.
Scoop dough into tablespoon rounds and place on an ungreased baking sheet or silicone mat/parchment paper lined baking sheet.
Bake 10-12 minutes, or until edges are light golden brown.
Cool cookies on baking sheet for a few minutes; transfer to a wire rack to cool completely. Eat & Enjoy!
Notes
Christmas M&M's Cookies in a Jar will keep for several months in the jar; ingredients will start to settle after a few weeks making the layers less visible.Christmas M&M's Cookies should be stored in an airtight container and will keep for 5+ days.