To make the crumb crust for Two-Layer Caramel-Pecan Bars, combine sugar, vanilla, salt, and butter in a medium bowl, and beat with a mixer at medium speed until well blended.
Add flour to the sugar mixture, and stir until blended. The mixture will be crumbly. Firmly press this mixture into the bottom of a greased 8-inch square baking pan.
Use your fingers to press the mixture evenly into the pan to make sure that it’s compact. It needs to be compact so that it will hold together when it’s cut.
Bake this crust layer at 375 degrees for 15 minutes.
While the crust is baking, make the mixture for the top layer. Combine caramel candies and milk in a saucepan, and cook over low heat for about 6 to 8 minutes until the candies melt, stirring occasionally. Stir in vanilla, and remove from the heat.
Remove the crust from the oven, and place the pan on a cooling rack. Pour the caramel mixture over the crust, and spread evenly.
Sprinkle the caramel mixture with chopped pecans, and bake at 375 degrees for 15 minutes.
Remove the pan from the oven and let the cookies cool completely in the pan on a wire rack.
Remove the entire square of cookies from the pan and place on a cutting board. Use a chef’s knife to cut the cookies into 4 equal strips, and then cut each strip crosswise into 5 pieces.