Applesauce Cake

0 About 15 minutes before cooking, combine applesauce, egg, and egg yolk in a small mixing bowl.
1 Let them sit out at room temperature. (Note: This is especially important if your applesauce has been in the refrigerator. Using room temperature applesauce and eggs will insure that the cake cooks evenly.)
2 Preheat oven to 350°F.
3 Spray an 8”x8” baking dish with nonstick cooking spray. 
4 In a large mixing bowl, whisk together the flour, pumpkin pie spice, baking powder, and salt until very well combined. 
5 To the bowl with the applesauce and eggs, whisk in brown sugar, vegetable oil, and vanilla extract until well combined.
6 Pour wet ingredients over dry ingredients and stir with a spatula just until combined (be careful not to overmix; a lighter touch here will lead to a more tender, moist cake).
7 Stir in any of the optional add-ins.
8 Pour batter into prepared pan.
9 Bake until the center of the cake is just set and edges are light golden brown, 28 to 30 minutes. (Note: If you added chopped apples to the cake, it may take up to 5 minutes longer to cook through since the apples may release moisture into the cake as it cooks.)
10 Let cake cool completely in the pan. Slice and serve.