Preheat oven to 350 degrees and line baking sheets with parchment paper
Stir together the flour, baking soda and salt and set aside
Cream the butter and both sugars together then add the eggs and vanilla and mix on low speed until combined
Add the flour, baking soda and salt and mix until in just combined
Fold in the M&Ms
Roll about 2 tablespoons at a time into balls and place on baking sheets
Flatten slightly and press a couple of M&Ms on the top before baking
Bake for 12 - 15 minutes until edges just begin to turn light brown, the cookies will still be soft
Remove from oven and cool on wire rack