Preheat your oven to 350 degrees F. Line two 4-inch round cake pans with parchment paper rounds and lightly grease the sides. If you only have one 4-inch pan, bake the layers one at a time.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt.
In a separate bowl, whisk the applesauce, maple syrup, oil, milk, and vanilla until smooth and well combined.
Pour the wet ingredients into the dry and gently fold with a spatula. Mix just until no streaks of flour remain. Do not overmix or the cake will get tough.
Add the apple cider vinegar last and quickly fold it in. You will see tiny bubbles start forming. Move fast from here so you do not lose the lift.
Divide the batter evenly between the two prepared pans, smoothing the tops.
Bake for 22 to 25 minutes, or until the tops spring back when lightly touched and a toothpick comes out clean or with a few moist crumbs.
Let the cakes cool in the pans for 10 minutes, then turn them out onto a wire rack to cool completely. The cakes must be fully cool before frosting.
While the cakes cool, make the vanilla frosting. In a saucepan, add vegan chocolate chips, coconut or almond oil and vegan butter. On low heat, continously stir it until everyrhing is combined and looks like frosting.
Place one cooled cake layer on a plate or small cake stand. Spread a generous layer of vanilla frosting on top. Add the second cake layer and frost the top and sides. Decorate with fresh fruit if using or specialty sprinkles
Refrigerate for at least 30 minutes before the smash session. This helps everything set up so it photographs beautifully (and actually stays put when baby goes for it).