Preheat oven 350 degrees.

Prepare an 8 1/2 x 11 glass baking pan with a layer of parchment paper and cooking spray or oil. Set aside.

Place the chocolate and butter, in a microwave safe glass bowl, and melt on high for 2 minutes – stopping to stir the chocolate every 30 seconds until fully melted. Stir in the sugar and vanilla. Mix in the eggs and flour. Pour the batter into the pan and bake for 12 minutes.

While the brownies are baking, mix the marshmallows, chocolate chips and walnuts. After baking for 12 minutes, remove the brownies from the oven and evenly distribute the marshmallows, walnuts and chocolate chips over the brownies, pressing them gently into the batter. Return the pan to the oven and bake for another 18-25 min. The brownies are done when you can insert a toothpick into the center and it comes out clean. Do not over bake.

Allow brownies to cool at room temperature on a wire rack. Once cool you may choose to refrigerate the brownies for an hour to set the chocolate and make them easier to cut. If not, serve warm and enjoy!