In a food processor, pulse your vanilla wafer cookies into a fine crumb. Also pulse your walnuts into a fine chop. Mix together until well blended. Next, mix in your brown sugar and mix well again. Now melt your butter and add to this mix and stir until well coated and mixture is crumbly.
Take one very full cup of crumb mixture and pour into a coated cake pan (I used 9") pressing into the bottom and spreading it evenly into the cake pans. Keep about 2 cups of the mixture which will be baked and used on the sides of the cake.
Set aside and start preparing the cake mix.
Preheat your oven to 350 degrees.
Beat the sugar and butter until light and fluffy.
Add in all the rest of the ingredients, except the eggs. Mix until well blended.
Add in the eggs, one at a time until just blended.
Pour your batter equally into your four prepared cake pans.
Place remaining crunch mixture in another cake pan or pie dish and allow to bake for the same amount of time as the cakes.
Bake at 350 degrees for 20-25 minutes. If using 8" cake pans, increase cooking time to 25-30 minutes or until a toothpick comes out clean.
Also remove the extra crunch mixture from the oven and break up any chunks that might have occurred while cooking.
Allow pans to cool about 10 minutes, then put them onto wire racks and allow to cool completely.
Whip the cream cheese and butter until smooth.
Slowly add in your powdered sugar and mix until well blended.
Add your vanilla until also well blended.
After your cake is cooled - begin frosting the layers and putting the cake together.
After putting together all of the layers with some frosting in between them, spread the remaining frosting on the sides and top.
If desired, add the extra crunch mixture to the top and sides of the cake.