Preheat oven to 350 degrees . Grease 8-inch square baking pan, line with parchment, then grease parchment. In bowl, whisk brown sugar, flour, cocoa, baking soda and salt. Make a well in center. Whisk eggs and vanilla into the well to blend. Gradually whisk in coffee and butter, then whisk in surrounding dry ingredients. Stir in chocolate chips; transfer batter to pan. Bake until toothpick inserted in center comes out clean, about 40 minutes. Let cool in pan on rack. Dust with confectioners sugar. Cut into 16 squares; serve with whipped cream.