• Place the avocado oil, sour cream, eggs, vanilla, salt, flour, sugar, brown sugar, baking soda, baking powder, cinnamon, nutmeg, and allspice in your bread machine pan.
• Select the quick bread, cake, or dessert program and press start. Choose a light or medium crust.
• While the batter mixes, toss the diced apple with the 2 tablespoons brown sugar, 1 teaspoon cinnamon, and 1 tablespoon flour until coated. When the add-in beeper goes off, add the apple and the walnuts.
• When the bread is done baking, check the temperature. It should be 200 to 205°F. If it isn’t, use the machine's extended baking time function (sometimes a custom function) to continue baking; it is fully cooked in my Zojirushi bread machine.
• Use oven mitts to immediately remove the bread pan from the machine.
• Let cool for 15 minutes, then remove from the pan.
• Allow to cool completely on a cooling rack before slicing.

For the Optional Glaze

• Melt the butter in a small saucepan over medium heat. Add the brown sugar, cream, and salt and whisk until smooth. Bring to a gentle boil and let it bubble for 1 minute, whisking, so the sugar dissolves and the caramel thickens slightly.
• Take the pan off the heat and whisk in the vanilla. Let it cool for about 5 minutes so it is warm, not hot.
• Whisk in the powdered sugar a little at a time until the glaze coats the back of a spoon and falls in a ribbon. Add more powdered sugar for a thicker drizzle or a splash of cream to loosen it.
• Drizzle over the fully cooled loaf. Let it set for about 15 m