Begin by preheating your oven to 180°C (350°F) and covering a baking sheet with parchment paper.
Take a mixing bowl and beat the softened butter, granulated sugar, and brown sugar until they become light and fluffy.
Add the eggs and vanilla extract to the mixture, beating until they are thoroughly incorporated.
In another bowl, combine the all-purpose flour, baking soda, and salt, whisking them together.
Gradually add the dry ingredients into the wet mixture, stirring until a cookie dough forms.
Gently fold in the M&M candies, ensuring they are evenly distributed throughout the dough.
Use a tablespoon to scoop out portions of cookie dough and place them on the prepared baking sheet, making sure to leave sufficient space between each cookie.
Optionally, refrigerate the cookie dough for approximately 30 minutes at this stage for slightly thicker cookies.
Bake the cookies in the preheated oven for 10-12 minutes, or until the edges turn golden while the centres remain soft.
After removing them from the oven, allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.