In a bowl, combine flour, baking soda and salt. Whisk to combine. Set aside.

In a mixing bowl, cream together shortening and both sugars until well combined. Add eggs and vanilla and mix to combine again.

Add flour mixture to the butter mixture and mix until fully combined. Fold the M&Ms in with a spatula or wooden spoon, making sure that the M&Ms are evenly mixed throughout the cookie batter.

Refrigerate the dough for several hours (or overnight) until completely chilled through.

When ready to bake, position oven rack to be in the upper 1/3^rd of the oven. Preheat oven to 350 degrees F.  Line baking sheets with a piece of parchment paper.

Using a large scoop, portion out your cookie dough into about 18 balls total (we used a scoop similar to this one).  You’ll bake 6 balls of dough per batch (refrigerate the remaining dough that is waiting to be baked.) Take each ball of cookie dough and roll it into smooth balls.  Evenly space the 6 balls of dough per cookie sheet, pressing down slightly to flatten and gently press a few extra M&Ms on the top of each ball if desired.

Bake for 10-12 minutes, rotating the cookie sheet after 5 minutes. Once the cookies are lightly golden around the bottom edges (it’s OK if the centers are still slightly soft), remove the cookie sheet from the oven. Allow the cookies to cool on the hot cookie sheet for 10 minutes before moving to a rack to cool completely (this extra time on the cookie sheet will allow the centers of the cookies to firm up.)