Preheat your oven to 350°F (175°C). In a microwave-safe bowl, combine the unsweetened chocolate and butter. Heat in the microwave in 30-second intervals, stirring after each until smooth.
In a large mixing bowl, whisk together the melted chocolate mixture with sugar until glossy. Add eggs one at a time, mixing well after each. Stir in vanilla extract.
In a separate bowl, sift together flour and salt. Gradually fold dry ingredients into the chocolate mixture until just combined.
Gently fold in 1 cup of the M&Ms or chocolate chips, reserving ½ cup for topping.
Drop rounded tablespoons of dough onto a lined baking sheet, leaving space between each cookie.
Sprinkle the reserved M&Ms on top of each cookie dough mound.
Bake for 12 to 15 minutes, or until edges are set. Let cool on the baking sheet for 5 minutes before transferring to a cooling rack.
Enjoy your cookies warm or at room temperature!
