• Preheat oven to 350℉ degrees.
• Roughly chop 1 cup of semi-sweet chocolate chips using a knife, rolling pin, or meat mallet (if not using a knife, place chips in a plastic bag while crushing). Set aside.
• Warm the unsalted butter (½ cup, i.e. 1 stick) in a microwave-safe bowl or saucepan until it’s just melted.
• Combine the melted unsalted butter with the light brown sugar (½ cup) and granulated sugar (¼ cup) in a mixing bowl and use a wooden spoon or spatula to stir them together (*do not use a mixer!).
• Next, stir in the egg (1 large), vanilla extract (2 teaspoons), and peppermint extract (½ teaspoon), followed by the baking soda (½ teaspoon) and salt (½ teaspoon). Mix in unsweetened dark cocoa powder (½ cup) and all-purpose flour (1 cup) until well-combined, then stir in chopped chocolate chips.
• Immediately spread dough into a greased cookie cake pan or DIY foil pan.
• Bake at 350° degrees with timing dependent on the type of pan (see my DIY foil pan hack in the post above). Bake the center no longer looks super wet. 

  For metal pan: Bake for 12-14 minutes.

  For foil pan (spray foil with nonstick cooking spray): Bake for 16-18 minutes.
• Cool completely before spreading on chocolate.

To Make Chocolate:

• Add whole semi-sweet chocolate chips (1 cup) and unsalted butter (¼ cup, i.e. ½ stick) to a small to medium-sized microwave-safe bowl. Heat on 50% power for 30-second increments until fully melted, stirring in between. Microwaving on 50% power is important to melt the chocolate slowly to prevent the chocolate from seizing or burning.
• Once melted, add in the peppermint extract (¼ teaspoon) and stir. Before spreading, set aside about 2 tablespoons of chocolate for the drizzle
• Spread melted chocolate over cooled cookie cake until tops and sides are covered. Place the 2 tablespoons of reserved chocolate in a piping bag or ziploc bag with a tiny corner cut off, then drizzle over top for added presentation.
• Allow chocolate to harden before cutting, then slice and enjoy!