Preheat oven to 375 F degrees
Prepare 9" removable bottom tart pan by greasing and flouring it.
SHORTBREAD CRUST:
Add flour, brown sugar and salt into bowl of food processor*. Blend a bit and add butter one Tbsp at a time and mix between each addition. Process until small crumbs form, similar to wet sand.
Pour into prepared pan, spread evenly and press to make solid layer and sides.
Bake for 10 minutes.
Let cool 5 minutes.
CREAM CHEESE LAYER:
Place cream cheese, powdered sugar and vanilla in bowl of mixer. Mix until light and fluffy.
ASSEMBLY:
Pour the cream cheese mixture over the bottom of the crust, spread evenly with off-set spatula.
Pour the 2 cups of walnuts over the cream cheese mixture evenly.
Pour the butterscotch over the walnuts evenly.
Arrange additional walnuts on top of butterscotch around the edge and in the center.
Bake 14 minutes or until butterscotch is bubbling.
Let cool completely.
Remove from tart pan, serve.