Preheat the oven to 350 degrees F.
Bring a pot of water to a boil and place a metal bowl or double boiler over it; make sure the bowl is not touching the water. Add the butter and chocolate squares to the bowl and stir until melted. Pour the melted chocolate into a large glass bowl. Add the sugar, flour, nuts, vanilla and eggs, and mix well.
Line a 13- by 9- by 2-inch baking dish with parchment paper. Rub the parchment paper with butter to prevent sticking. Then pour the brownie batter into the dish. Bake until a wooden toothpick inserted in the center comes out clean, about 30 minutes. Remove the brownies from the oven.
Use the parchment paper to lift the brownies from the baking dish. Cut into bars. Serve warm with vanilla ice cream and drizzle with Caramel Sauce. Garnish with additional toppings as desired.
In a large saucepan, combine the sugar and 1 1/2 cups water. Cook and stir over high heat until the sugar is dissolved and the mixture comes to a boil. Reduce the heat to medium. Continue cooking, stirring occasionally, until the mixture is a golden color.
Remove from the heat. Carefully whisk in the cream, half at a time. Stir in the butter and vanilla. Return to medium heat to melt any sugar lumps. Let cool.