Take the eggs out of the refrigerator 30 minutes before you start baking to bring them to room temperature.

In a mixing bowl, melt the butter according to the instructions on the brownie mix box. Let it cool slightly.

In a separate mixing bowl, whisk together the brownie mix, all-purpose flour, and powdered sugar.

Add the room-temperature eggs, vanilla extract, and vegetable oil to the melted butter. Mix until well combined.

Gradually fold the dry ingredient mixture into the wet mixture until a thick cookie dough forms.

Gently fold in the M&M candies and chocolate chips if you're using them. This will give your cookies an extra burst of chocolatey goodness.

Cover the mixing bowl with plastic wrap and chill the dough in the refrigerator for at least 1 hour. Chilling the dough helps prevent the cookies from spreading too much during baking and gives them a fudgy texture.

Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper or a silicone baking mat.

Using a cookie scoop or a spoon, drop rounded tablespoons of cookie dough onto the prepared baking sheet, spacing them about 2 inches apart. This allows room for the cookies to spread as they bake.

Bake in the preheated oven for 14-16 minutes or until the edges are set and the centers are slightly soft. Be careful not to overbake; the cookies will continue to firm up as they cool.

Remove the cookies from the oven and let them cool on the baking sheet for a few minutes to set. Then, transfer them to a wire rack to cool completely.

Once the cookies are completely cooled, enjoy their rich, chocolaty, and crunchy goodness!