In a medium size bowl, whisk together flour, baking soda, and salt. Set aside.
In a large bowl using an electric mixer, cream together butter and sugars on high speed until smooth and pale. Add the egg, egg yolk and vanilla extract; mix until combined.
Slowly add flour mixture to wet ingredients; mix just until combined.
Scoop dough into 1.5" rounds, or use a #50 disher to scoop balls of dough. Place on a silicone mat/parchment paper lined baking sheet 2-3" apart. Cookies will spread significantly. Using your fingers slightly flatten balls of dough.
Bake 10-11 minutes or until barely golden brown around the edges. Do not overbake. Cookies may appear to be soft and undone, but they will set as they cool.
Immediately remove cookies and press M&M's into the tops of the cookies. Place back in oven and bake for 30 seconds to melt M&M's into place.
Cool cookies on baking sheet on wire rack for 5 minutes; transfer to a wire rack to cool completely. Eat & Enjoy!
Chewy M&M Cookies should be stored in an airtight container and will keep 4+ days.Recipe from The Baker Chick.
Chewy M&M Cookies | https://sarahsbakestudio.com/chewy-mm-cookies/