Brownies: Preheat oven to 350ºF. Using a spoon, stir eggs with 3/4-cup sugar and 1 teaspoon vanilla; add butter. Sift ground chocolate with flour, baking powder, and salt. Stir into egg mixture; add nuts. Stir in chips. Spread into greased 8" or 9" square pan. Bake 20 to 30 minutes. For extra chewy brownies, use 8" pan and less baking time. For cake-like brownies, use 9" pan and longer baking time. Cut into squares.
Caramel Pecan Topping: Once brownie is baked and cooled, in a 3-quart saucepan, bring 3/4-cup sugar, corn syrup, water, and a pinch of salt to a boil until it turns a golden caramel. Remove pan from heat, and slowly add cream and 1 teaspoon vanilla. Quickly stir in pecans, and pour over brownie layer. Cool on rack. Chill brownies, covered, until caramel is firm (2 hours).