Preheat oven to 350 degrees. Cream butter and brown sugar in a large bowl until light and fluffy. Add flour and nuts. Blend until the mixture resembles crumbs and set aside 3/4 cup, press the remaining mixture into the bottom of an 8″ square pan. Bake for 15 minutes. Combine the sugar and the cream cheese in a medium bowl and beat until smooth, add the egg, milk, lemon juice and vanilla, beating well. Spread the cream cheese mixture over the baked crust. Sprinkle the reserved 3/4 cup of crumbs over the top. Bake for 25 minutes. Cool for 1 hour in the refrigerator and cut into bars.