Preheat the oven to 350°F and line an 8"x8" baking dish with parchment paper then set it aside.
In a large bowl, whisk together the milk and vinegar, allowing it to curdle for 5-10 minutes. Next, add the brown sugar, oil, applesauce, and vanilla to the curdled milk mixture and whisk well.
In a separate bowl, whisk together the flour, salt, and baking powder. Then, combine the dry and wet ingredients, mixing to form a smooth batter.
Pour half of the batter into the prepared baking pan.
In another bowl, mix together all of the ingredients for the toppings. Then, spread half of the nut mixture on top of the batter in the pan.
Add the remaining batter on top of the nut mixture, smoothing it out evenly. Sprinkle the remaining nut mixture on top of the batter.
Cover the pan with foil and bake for 20 minutes. Remove the foil and bake for an additional 25 minutes.
When the cake is done baking, let it cool down for 10-15 minutes. Then, whisk together the ingredients for the syrup. Drizzle or brush the syrup on top of the cake and let it cool down completely before serving.