Preheat oven to 350 degrees
Beat together butter and sugar until light and fluffy
Blend in eggs and vanilla extract
Combine flour, soda, and salt
Slowly add dry ingredients, mix well, and add M&M's
Form dough into golf ball size rounds and place on baking sheet about 4 or 5 inches apart
Press 3 to 4 additional candies into top of each cookie
Bake for 12-14 minutes or until lightly browned
Cool on cookie sheet about 3 minutes
Remove and place on wire rack to cool thoroughly