Preheat oven to 350F. Grease a 9x13 baking pan.

Crust: In a medium bowl, whisk together flour and ground walnuts. Using a pastry blender, cut butter into flour mixture until crumbly and no butter remains larger than a pea. Turn mixture into prepared pan and press into an even layer. Bake until lightly brown around the edges, about 15 minutes. Remove from oven and cool completely.

Cheesecake: Using an electric mixer on medium speed, beat cream cheese, powdered sugar, and milk until smooth, 2-3 minutes. Spread in an even layer over cooled crust.

Sprinkle chopped walnuts over cream cheese layer, then spread Cool Whip in an even layer on top of walnuts. Spoon pie filling on top of Cool Whip. Cover with plastic wrap and refrigerate overnight before serving. Leftovers should be stored, covered, in the refrigerator, for up to 4 days.