1. Preheat oven to 350°F. Grease a 9-inch square baking pan and line with parchment paper. In a large mixing bowl, whisk together melted butter, brown sugar, egg and vanilla extract until well combined.
2. Sprinkle baking powder, baking soda and salt into the bowl then whisk together. Sprinkle flour into the bowl and fold to combine (try not to overmix).
3. Add chocolate chips, marshmallows and cornflakes then fold until just combined. Pour batter into prepared baking pan and use an offset spatula (or a spoon) to spread the batter to all 4 corners of the pan (the batter is very thick).
4. Bake for 20 minutes or when a toothpick inserted in the center comes out clean. The brownies should be lightly browned on top. Let brownies cool in the pan for at least 30 minutes before removing from the pan. Cut into 9 equal pieces and top with sauce (see recipe below). Enjoy!

Salted White Chocolate Maple Butter

1. While the brownies are baking, make the sauce: Prepare a double boiler by placing a small mixing bowl over a saucepan filled about 1 inch with water. Turn heat to medium then add white chocolate chips, heavy cream and maple syrup to the mixing bowl.
2. Allow the chocolate to melt slowly, stirring occasionally. Meanwhile, brown the butter in a small skillet over medium heat. Stir the butter constantly for about 5 minutes until butter begins to foam and brown. You will smell a deep nutty flavor develop.
3. Pour the butter directly into the mixing bowl with the chocolate, cream and syrup and stir until chocolate is melted and the sauce is smooth and creamy. Pour over cooled brownies.