This is a Bakehouse classic is Zingerman's most popular coffee cake. Rich and moist from the real sour cream made at Guernsey family dairy in Northville, MI, and loaded with a distinctive cinnamon-nut swirl made with Indonesian korintje cinnamon, brown sugar and freshly toasted walnuts and then bake it in a traditional bundt pan. And it lasts. A week or two later, on the counter, it will still be scrumptious and it freezes beautifully, for up to a month.