1. Preheat the oven to 350 degrees F and line your cake pan with parchment paper leaving enough overhang to be able to remove the cake.
2. In a large bowl whisk together the sourdough starter, applesauce, oil, sour cream or Greek yogurt, white sugar, brown sugar, egg, and vanilla extract until smooth.
3. In a separate bowl whisk together the flour, baking powder, baking soda, salt, cinnamon, nutmeg. ginger, cloves, and cardamom.
4. Fold dry mixture into wet mixture until just combined. Stir in nuts if using. Be careful not to over-mix here.
5. Pour the batter into the cake pan and spread evenly bake for 35-40 minutes or until a toothpick inserted into the center comes out clean. A few moist crumbs are okay.
6. Allow sourdough applesauce to cool for 10-15 minutes in the pan before transferring to a wire rack to cool completely.

How to make the frosting

1. Beat cream cheese and butter until smooth. Add the powdered sugar and vanilla and beat until light and fluffy. Spread the frosting evenly over the cake.
2. Caramel drizzle: In a small saucepan, melt the butter and brown sugar together. Stir in the heavy cream and simmer 1-2 minutes until smooth. Remove from heat and stir in the pinch of salt. Let cool sightly to thicken.
3. If the glaze thickens too much add a splash of milk to thin it out.
4. Drizzle the caramel glaze over top of the cake and gently swirl it around with a spoon for a marbled effect. Slice, serve, and enjoy!
5. Sourdough applesauce cake lasts for 4-5 days in the fridge in an airtight container.