In a saucepan or the microwave, melt the butter
In a large bowl, with an electric mixer, beat together the butter and sugar until light and fluffy
Blend in eggs and vanilla extract
In a separate bowl, combine flour, soda, and salt
Slowly add the dry ingredients into the wet ingredients and mix well
Stir in the M&M's
Form the dough into golf ball size rounds and place on a baking sheet 4-5 inches apart
Press 3-4 additional candies into each cookie
Bake 12-14 minutes, until lightly browned
Cool on the baking sheet for about 3 minutes, then transfer to a wire rack to cool completely