Heat oven to 180ºC Using a spoon, stir eggs with sugar and vanilla; add butter. Sift Ground Chocolate with flour, baking powder and salt. Stir into egg mixture; add nuts. Spread into greased 8 or 23 cm square pan. Bake at 180ºC for 20-30 minutes. For extra chewy brownies, use 20 cm pan and less baking time. For cake like brownies use 23 cm pan and longer baking. Cut into squares.