Preheat oven to 350 degrees F (175 degrees C). Grease a 9 x 5 x 3 inch loaf pan. Whisk the flour, oats, baking powder, salt and spices together in a large bowl; set aside.
Whisk the eggs in a mixing bowl until smooth. Whisk in the pears and sour cream. Add the sugar; mix until well blended. Fold into the dry mixture along with the apples and walnuts until no dry lumps remain. Pour into the prepared loaf pan.
Bake in preheated oven until a toothpick inserted into the center comes out clean, 45 to 50 minutes. Cool in the pan for 10 minutes before removing to cool completely on a wire rack.