In a medium mixing bowl, using an electric mixer, cream together the butter or margarine and brown sugar. Add the flour and walnuts or pecans; beat until the mixture is crumbly.
Set aside 1 cup of the crumb mixture for the topping. Press the remaining crumb mixture into the bottom of a 9-inch square baking pan. Bake the crust at 350 degrees for 12 minutes.
Meanwhile, in a large mixing bowl using the electric mixer, beat together the ¼ cup granulated sugar and the softened cream cheese until the mixture is smooth. Add the egg, milk, lemon juice and vanilla; beat just until the ingredients are combined.
Spread the cream cheese mixture over the hot crust. Sprinkle the reserved crumb mixture over the top. Bake in the 350 degree oven about 25 minutes or until the cheesecake is set. Remove the cheesecake from the oven, but do not turn off the oven.
Meanwhile, in a small bowl, stir together the sour cream and the ¼ cup granulated sugar until well mixed. Spread the sour cream mixture over the top of the hot cheesecake. Bake for 5 minutes more. Place the baking pan on a wire rack; cool completely. Makes 9 squares.
Source: “Cook and Love it More” Celeste Johnson, “America’s Best Loved Community Cookbook Recipes, Desserts, Better Homes and Gardens”, Meredith Corporation, 1996