• Preheat oven to 350°F (175°C). Line a baking sheet with parchment paper.
• Cream together the butter, brown sugar, and granulated sugar until light and fluffy.
• Beat in the eggs one at a time, then stir in the vanilla extract.
• In a separate bowl, whisk together flour, baking soda, salt, and cocoa powder.
• Gradually add dry ingredients to the butter mixture, mixing until just combined.
• Fold in the chocolate chips and M&Ms.
• Scoop tablespoons of dough onto the prepared baking sheet, about 2 inches apart.
• Create a small indent in the center of each cookie and fill with chocolate fudge.
• Bake for 10-12 minutes, until edges are set but centers are still soft.
• Allow cookies to cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.

Notes

• For extra fudgy centers, chill the dough for 30 minutes before baking.
• Use room temperature ingredients for best results.
• Avoid overmixing the dough to keep cookies tender.