Put oven rack in the middle. Pre heat oven at 350 F . Generously grease 8x8 pan and set aside.Melt butter in the microwave and pour into the mixing bowl. Add in sugar and mix until incorporated. Add the egg and vanilla extract and mix until smooth. In a separate bowl, mix flour,baking soda,baking powder and salt with wire whisk. slowly add dry ingredients to the wet ingredients and mix until combined. The mixture will look hard and crumbly,but that is okay. Add in the walnut and chocolate chips and mix by hand or spatula. Transfer mixture into a 8 x 8 greased baking pan.Flatten dough and Bake at preheated oven for 15-18 minutes no more,no less and remove from the oven. The dough will be soft,but let it continue cooking in the hot pan. Slice into 2 x 2 squares. Serve hot topped with ice cream and Maple Syrup.