Preheat the oven to 350°F (175°C).

Lightly grease the 8-inch round cake pan.

In a mixing bowl, combine the whole wheat flour, baking powder, baking soda, and salt.

In a separate bowl, whisk together the applesauce, honey (or maple syrup), milk, and vanilla extract.

Pour the wet ingredients into the dry ingredients and stir until just combined.

Transfer the batter to the prepared cake pan and smooth the top.

Bake the cake for 25 minutes or until a toothpick inserted comes out clean.

Allow the cake to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.