In a large bowl, melt the butter. Stir in the granulated sugar and brown sugar until combined. Add the eggs and vanilla extract, mixing well. In another bowl, whisk together the flour, cocoa powder, and salt. Gradually add the dry ingredients to the wet ingredients, stirring until just combined. Fold in the chopped hazelnuts.

Bake the Brownies

Pour the batter into the prepared baking pan and spread evenly. Bake for 25-30 minutes or until a toothpick inserted in the center comes out clean. Allow to cool completely.

Salted Caramel Sauce Preparation

Make the Caramel

In a medium saucepan over medium heat, melt the sugar, stirring continuously until it turns a golden brown color. Carefully add the butter and stir until melted. Slowly drizzle in the heavy cream while stirring constantly. Remove from heat and stir in the salt. Let it cool slightly.

Hot Fudge Sauce Preparation

Make the Hot Fudge

In a saucepan, combine chocolate chips, heavy cream, and butter over medium heat. Stir until the chocolate is melted and the mixture is smooth. Remove from heat and stir in the vanilla extract.

Assembly

Assemble the Dessert

Cut the cooled brownies into squares. Drizzle each brownie with salted caramel sauce and hot fudge sauce. Serve immediately.