Preheat the oven to 350 degrees F. Line a baking sheet with parchment paper.

In a medium bowl, beat together softened butter, granulated sugar, and light brown sugar until creamy.

Add eggs and vanilla extract; beat until light and fluffy.

In a separate bowl, whisk together flour, cocoa powder, baking soda, and salt.

Gradually add dry ingredients to wet ingredients, mixing until well combined.

Stir in 1 cup of M&M candies and set aside the rest for topping.

Refrigerate the dough for 30-60 minutes to prevent spreading.

Drop heaping tablespoons of dough onto the prepared baking sheet, about 2 inches apart.

Gently press remaining M&M candies on top of each cookie.

Bake for 8-11 minutes until edges are set and centers remain slightly glossy.

Allow cookies to cool on the baking sheet for 3 minutes, then transfer to a wire rack.