In a large bowl, beat together your butter and sugar until light and creamy.
Gradually mix in the eggs, one at a time, and then add your vanilla.
Beat at medium speed until thoroughly combined, and then add your flour, salt and baking powder and mix at low speed for one minute. You do not want to over-mix!
Split your dough into half and wrap in plastic wrap, refrigerating for one hour.
Begin by pre-heating your oven to 350 degrees F.
When you're ready to start baking, take one ball of dough out of the fridge and begin to shape the dough into small balls (about the size of a walnut) and place them two inches apart on un-greased cookie sheets.
Bake at 350 degrees F for about 12-15 minutes until lightly brown - this depends on your oven. Mine were turning light brown by the 13th minute. Remove them from the oven and immediately press an M&M into center of each cookie.
Note: If you are using regular M&Ms, you might want to put two M&Ms into each cookie because they're so much smaller.
Remove from sheet pan to a cooling rack and allow to cool completely!