Combine pecans, butter and flour. Pat into 9x13 pan. Bake at 350 degrees for 20 minutes and cool. Mix together cream cheese, powdered sugar, and 1-1/2 cups of Cool Whip. Gently pour over the crust. Combine puddings and milk. Beat with mixer. Stir in 1-1/2 cups of Cool Whip. Put on top of first layer. Grate Hershey bar on top. Cool and serve.