In a bowl add the butter, brown sugar, caster sugar and vanilla, mix to combine.
Sieve the dry ingredients and add to the liquid ingredients. Save about half a cup of the flour and add it gradually and if needed. Mix to combine and obtain a soft and somewhat sticky dough.
Make small lemon-sized cookie doughs. Add 1 or 2 M&Ms in each one and stick 1 or 2 M&Ms on top of each cookie.
Cook in a pre-heated oven at 180° Celsius (350° F) for about 30 minutes until slightly golden brown on the bottom.
Notes
You can add 100 grams of chocolate chips too, but these cookies are already sweet as it is. They keep well for a couple of days, if the household can keep themselves from eating. This recipe calls for peanut M&M's but all other types of M&Ms will also work fine. I have used wheat starch, corn starch can also be used.