Toasting the hazelnuts for these rich bars enriches their flavor.

Ingredients
1/2  cup butter, softened
2  3-ounce packages cream cheese, softened
1/2  cup packed brown sugar
2  cups all-purpose flour
2  cups granulated sugar
1-1/2  cups buttermilk
4   eggs
1/2  cup butter, melted
1/3  cup all-purpose flour
2  teaspoons vanilla
1/2  teaspoon salt
2  cups toasted chopped hazelnuts (optional)
   Sifted Powdered Sugar

Directions
1. For crust, in a large mixing bowl beat the 1/2 cup softened butter, cream cheese, brown sugar, and the 2 cups flour with an electric mixer on medium to high speed until well combined. With lightly floured hands pat mixture onto the bottom and up sides of an ungreased 15x10x1-inch baking pan. Bake in a 350 degree F oven for 15 minutes.

2. Meanwhile, for filling, in a medium mixing bowl beat together granulated sugar, buttermilk, eggs, the 1/2 cup melted butter, the 1/3 cup flour, vanilla, and salt with an electric mixer on low speed until combined. Stir in nuts. Pour into crust.

3. Bake in a 350 degree F oven for 35 minutes or until golden. Cool completely in pan on a wire rack. Cut into bars. Sprinkle with powdered sugar. Store bars in the refrigerator. Makes 48. 

Source:  Better Homes & Gardens