An adopted recipe originally posted by Mean Chef who noted "makes two 9 by 5 inch or 8 1/2 by 4 1/2 inch loaves". From the reviews on the recipe I would suggest you use a very fragrant tasty apple, I like Northern Spy.
Butter and flour two 6- to 8-cup loaf pans and reserve.
In a mixer, cream together the butter, oil and sugars.
Add the eggs, vanilla and sour cream.
Sift together the cardamom, salt, baking powder, baking soda and flour.
Mix into the creamed ingredients, a little at a time, until incorporated, taking care not to overmix.
Stir in the walnuts and apple.
Divide batter between the prepared pans.
Tap pans on the counter to remove any air bubbles.
Bake for approximately 60 to 65 minutes, or until a toothpick poked in centers comes out clean.
Rotate pans halfway through baking.
After 45 minutes, place sheets of foil loosely over loaves to prevent overbrowning.
(Ovens bake differently, so use your best judgment and a doneness test when gauging cooking time for baked goods.) Cool in pans for 10 minutes, then remove to a rack and turn right-side-up to cool completely.