Preheat oven to 350°F/180°C. Line cookie trays with parchment paper.
Whisk together the flour, baking soda, baking powder and salt in a small bowl. Set the dry ingredients aside.190 g all-purpose flour, ½ teaspoon baking soda, ¼ tsp baking powder, ½ teaspoon salt
In a large bowl, beat the butter, sugars and vanilla together with an electric mixer until light and creamy. 113 g butter, 100 g soft brown sugar, 50 g granulated sugar, 1 teaspoon vanilla paste
Beat in the egg. 1 large egg
Add the flour mixture to the wet ingredients and stir them with a rubber spatula or wooden spoon until mainly all combined, but with a few streaks of flour remaining.
Stir through the mini M&M's. 180 g mini M&Ms
Use a cookie scoop or a tablespoon to take around 1.5 tablespoons of dough per cookie. Roll it into a ball.
Space the cookie balls at least 2 inches/5 cm apart on each prepared baking sheet.
Bake the cookies for around 10-12 minutes until the edges of the cookie are golden brown, but the middles are still soft.
For extra round cookies, when they are just out of the oven, place a large cookie cutter over the hot cookie on the cookie sheet, then swirl it gently around the cookie. It will push it into a perfect cookie shape.
Press a few extra M&Ms on top of the hot cookie.
Once baked, let the cookies cool on their trays for around 5 minutes before transferring them to a cooling rack and cooling them further.
Notes
Both metric and US customary measurements are provided. Use the toggle on the recipe card to switch between the two.