In mixer, beat shortening and sugars until well blended. The longer the better.
Add eggs and vanilla. Beat until smooth.
Add the flour a little at a time until well blended. Remove from mixer.
Add the M & M's and stir in by hand so the candies do not get all broken into pieces.
Spray cookie sheets lightly. I use a small ice cream scoop to scoop dough onto cookie sheets.
Bake at 375 degrees for about 10 minutes. You want the cookies to be browning around the edges only. Keep in mind that cookies on baking sheets bake for an additional minute or so when removed from oven.
Cool slightly and take a spatula and place on paper towels to finish cooling. Store in air tight container when completely cooled. This recipe and the scoop I use makes 24 nice sized cookies.