This recipe for walnut crust is very good when used with the buttermilk flan filling. Substituting rolled oats for some of the flour in the crust should also give a good result. Crust: \1 1⁄2 cups whole wheat flour 1 cup ground walnut 1⁄4 cup sugar 1⁄2 cup unsalted butter, softened 1 large egg, lightly…