Preheat the oven to 350 degrees. Prepare a loaf pan by spraying with nonstick spray, lining the bottom with parchment paper and spraying again. Set aside.
In a medium bowl, whisk together the flour, baking soda, baking powder, salt and spices.
In a large bowl, whisk together the oil, both sugars, vanilla extract, egg, and apple butter. Mix in the grated apples if using.
Add half of the dry ingredients into wet ingredients and mix. Add the buttermilk and stir. Add in remaining dry ingredients and stir until combined.
Pour the batter into the prepared loaf pan. Bake for 50-60 minutes. Test to see if it is done by inserting a toothpick into the center. It is done when it comes out clean or with just a few crumbs.
While the cake is cooling, combine all glaze ingredients and stir until smooth. Just prior to glazing, heat in microwave in 30-second increments, stirring in-between, until liquid enough to drizzle over cake.
Let the cake cool 15 to 20 minutes in the pan then turn it out onto a wire rack to cool completely before drizzling it with the glaze.
Notes
STORE/FREEZETo store: Place the cake in an airtight container and store it in the refrigerator for up to 4 days. Note the glaze will soak into the cake while being refrigerated.To freeze: It is best to freeze the cake unglazed. Wrap the cake first in plastic wrap and then with aluminum foil. Place the glaze in a freezer-safe container. Freeze for up to 3 months. Thaw both the cake and glaze in the fridge overnight.