Preheat oven to 350°F.
Prepare 2 cake pans that are between 7" to 8" wide. You can also bake one at a time if you only have 1 pan. Generously oil or butter the pans and then dust with an even layer of flour to help easily remove the cake from the pans.
In small mixing bowl, whisk together the soy milk and apple cider vinegar and set aside to curdle for about 5 to 10 minutes.
In a large mixing bowl, sift together flour, baking powder, baking soda, cinnamon, all-spice, ginger, and sea salt.
Once the soy milk and vinegar has thickened, add brown sugar, oil, molasses and vanilla extract and combine until smooth.
Add the liquid ingredients and shredded apple to the dry ingredients. Fold the batter until it’s just combined, ensuring not to over mix it. Small lumps in the batter are fine, but you shouldn't see pockets of dry ingredients that aren't incorporated.
Divide the batter evenly between the cake pans. Spread out the batter so it’s even and to the edge of the pan.
Bake for 15 to 18 minutes on the centre rack. Cake is done when a toothpick comes out mostly clean from the centre of the cake.
Allow the cakes to cool on wire racks for 10 to 15 minutes before removing them from the cake pans. To remove the cakes, place the wire rack on top of the cake pan and flip it upside down. Let the cakes cool completely before frosting and assembling.
To make the frosting, beat the chilled vegan butter with about ¼ cup of powdered sugar in a food processor, with a hand mixer, or in a stand mixer. Only once combined and smooth, add a bit more sugar and then add a little bit of maple syrup. Continue mixing portions of sugar and maple syrup along with the soy milk until a smooth and fluffy frosting is achieved. Be sure you don't add any liquid too soon in the process, as it can sometimes start to separate the butter.
Place one cake bottom side down on your serving plate and spread frosting evenly with a spatula across the entire top of the cake. Place the other cake, bottom side down, on top of the frosting. Use remaining frosting to cover the entire cake.
Using the palm of your hands, gently press small handfuls of roughly chopped pecans along the entire side of the cake until well coated. The cake is best served the same day as baking and frosting. Leftovers can be stored in the fridge or at room temperature for 2 to 3 days. If refrigerated, let cake sit at room temperature before consuming to take the chill off.