Cream butter with brown sugar in a small mixing bowl. Add walnuts and flour; mix to make a crumb mixture. Reserve 2 cups for topping. Press the remaining mixture into the bottom of a 9x13 pan. Bake for 12-15 minutes until lightly browned.
Blend sugar with cream cheese in a mixing bowl until smooth. Add egg, milk, lemon juice and vanilla extract. Beat well. Spread over baked crust.
Sprinkle reserved crumb mixture over cream cheese layer. Bake for 25 minutes.
Cool before cutting. Store covered in the refrigerator.
This recipe was calculated using the exact brands and measurements I used to make this recipe. If you are following a strict diet please note changing anything will cause the nutritional info to change. My calculations are intended as a guide only.