Pre-heat the oven to 350 degrees F. Cover an 8×8 inch square baking pan with two pieces of foil so that it comes up both sides of the pan. Grease with butter or coat lightly with cooking spray. Using a small saucepan and metal or glass bowl, create a double-boiler by filling the saucepan with about 2-3 inches of water. Place the bowl over the saucepan (the water shouldn’t touch the bottom of the bowl) and melt the butter and chocolate over a low flame. Add the salt and cocoa nibs. Stir constantly until the mixture is smooth. Remove the bowl from the heat and add the sugar and the eggs, one at a time. Stir until smooth.
Sift together the corn starch and cocoa powder in a large bowl. Pour the chocolate mixture over the dry ingredients in the large bowl. Stir well to combine. With a hand mixer, beat the batter until it’s smooth and the sugar has dissolved. Blend for a least 1-2 minutes, this adds volume to the batter. Add the toasted walnuts, if using. Pour the batter into the prepared greased pan.
Bake the brownies for 20-30 minutes or until the center is just set. Don’t over bake them, this is an ooey-gooey brownie. Let the brownies cool in the pan before removing and slicing. The brownies are good at room temperature for 4 days and can be frozen for up to a month.