Preheat the oven to 350℉ (180℃) conventional (see note 2 if using a convection oven). Lightly grease a 9x13-inch cake pan and line it lengthways with parchment paper, leaving some overhang on the sides so it is easy to lift out later. Set aside.
In a medium bowl, sift together the flour, cornstarch, baking powder, baking soda, salt, cinnamon, ground ginger, ground cloves, and ground nutmeg. Using a whisk, mix until well combined. Set aside.
In a large bowl, combine the light brown sugar, eggs, vegetable oil, applesauce, milk, and vanilla. Using a whisk, mix until smooth and well combined.
Add the pre-sifted dry ingredients into the wet mixture and, using a spatula, gently fold until just combined. Be careful not to overmix and only fold until you no longer see any streaks of flour. The batter may look slightly lumpy, but that's perfectly fine as long as there aren't any large clumps.
Pour the batter into the prepared cake pan and spread it into an even layer. Gently tap the pan on the counter to release any large air bubbles.
Bake for 25–27 minutes, or until a toothpick inserted into the centre comes out clean or with a few moist crumbs attached.
Allow the cake to cool in the pan for about 15 minutes. Run a thin knife along the edges without parchment, then carefully turn it out onto a wire rack and remove the parchment paper (see video for the easiest way to flip the cake). If desired, flip it back over so it is right side up to avoid wire rack marks on the surface. Cool completely before dusting with powdered sugar, slicing, and serving. Enjoy!