01 -
Heat your oven to 350°F. Line an 8×8 or 9×9 inch baking dish with foil and spray with nonstick spray, or just spray the pan directly.
02 -
Melt butter in a saucepan over medium heat, stirring occasionally. The butter will foam, then settle, and start forming light brown bits. When it smells nutty and looks amber-colored, it's ready. (You can skip browning and just melt the butter if you prefer.)
03 -
While the butter browns, combine sugar, cocoa powder, and salt in a bowl. Pour the hot browned butter over this mixture and beat until smooth. Add water and vanilla, then quickly mix in the eggs before they can curdle.
04 -
Add flour and chocolate chips, mixing just until combined. The batter will be very thick, like cement. Spread it evenly in your prepared pan using a sturdy spatula.
05 -
Bake for 25-30 minutes until a toothpick comes out clean. Let cool completely (or speed things up by placing in the freezer for about 10 minutes).
06 -
Remove foil from marshmallow creme jar and microwave for 15-20 seconds until it just starts to puff up. Scoop into a bowl, add peppermint extract and green food coloring, and mix well.
07 -
Spread the mint marshmallow mixture over the cooled brownies. Sprinkle with chopped Thin Mints, pressing them in lightly. Let the marshmallow layer set before cutting into squares.