Preheat your oven to 350°F (175°C) and grease a 9x13-inch baking pan.

In a large bowl, whisk together the flour, baking powder, baking soda, salt, cinnamon, ginger, and nutmeg until well combined.

In another large bowl, whisk together the vegetable oil, white sugar, brown sugar, eggs, and vanilla extract until well blended and smooth.

Stir in the applesauce, grated apple, and sour cream until well incorporated.

Gradually add the flour mixture to the wet mixture, beating on low speed until just combined.

Pour the batter into the prepared baking pan and bake for 40-45 minutes, or until a toothpick inserted in the center comes out clean.

Once baked, let the cake cool in the pan for about 15 minutes before transferring to a wire rack.

For the cream cheese frosting, beat the softened butter in a bowl until smooth.

Gradually mix in the cream cheese until creamy, then add powdered sugar one cup at a time. Beat until fluffy, adding heavy cream as necessary to achieve desired consistency.

Once the cake is completely cool, frost the top with the cream cheese frosting and sprinkle with chopped walnuts if desired.

Slice and serve, enjoying every bite with loved ones or savoring a piece on your own.