Cardamom Coffee Cake

Preheat oven to 350 deg. F. Grease and flour a 10-inch tube or bundt pan. In a _large_ (she's not kidding, folks) mixing bowl, beat butter with 2 cups brown sugar until light and fluffy. Add eggs, one at a time, beating well after each. Stir in the vanilla. Sift together the flour, baking powder, soda, salt, and cardamom in a separate bowl. Add the flour mixture, 1/3 of it at a time, to the butter mixture, alternating with the sour cream. Stir just enough to blend after each addition. Don't beat or otherwise overmix. Combine 1/4 cup brown sugar, cinnamon, and walnuts in a separate small bowl. Spoon approximately 1/3 of the batter into the prepared pan. Sprinkle with half the nut mixture, then add another third of the batter. Cover with remaining nut mixture, then top with remaining batter. Lightly spread into place. Bake approximately 1-1/4 hours or until a knife inserted all the way in comes out clean. Allow to cool in the pan for 20 minutes, then invert onto a plate. Cool at least 30 minutes more before cutting into it. (Note: It really does take that long - or even longer - to bake. The batter may overflow the pan during baking, so spread some aluminum foil to catch any drips.) Serves 18