Start by getting out everything you need, this is good for two reasons. 1 you will have everything at your finger tips and 2 it lets you make sure you have everything before you begin!
Combine your dry ingredients and set aside.
Beat the butter (room temp) and sugars together with an electric mixer until light,pale and creamy. Then beat in the eggs and vanilla. combine the dry ingredients with the sugar and egg mixture. Beat until the mixture combines and forms a soft dough.
Add as many m&m's as you like I put in about half a packet.
Place the dough in the fridge for about 30 mins or until chilled and firm.
Bake for about 10- 12 mins. Don't over cook or they won't be chewy in the middle like subway cookies! Cool and enjoy x