• Preheat the oven to 350°F (180°C). Line a 9-inch x 13-inch pan with parchment paper and lightly oil paper. You can also use a 10-inch round pan, but the cake takes longer to bake and comes out thicker.
• In a medium bowl, stir almond milk and apple cider vinegar. Set aside 5 minutes until it curdles. This is the vegan buttermilk.
• In a large bowl, whisk flour, baking powder, baking soda, cinnamon, ginger, and salt. Set aside.
• In another large bowl, whisk the vegan buttermilk made before, melted vegan butter, unsweetened apple sauce, and soft brown sugar.
• Stir the dry ingredients with the wet ingredients until a smooth cake batter forms. Don't over-stir it.
• Fold in the chopped apples and transfer the cake batter into the prepared pan.
• To make the toppings, place the softened vegan butter, vanilla, sugar, and cinnamon in a bowl. Press with a fork or crumble between your fingertips until it resembles a crumbly buttery mixture.
• Sprinkle the cinnamon sugar all over the top of the vegan apple cake.
• Sprinkle slivered almonds and place some of the apple slices on the cake.
• Bake on the center rack of the oven for 50 to 80 minutes or until a toothpick inserted in the center of the cake comes out clean. If the top browns too fast, tent the pan with a large piece of foil.
• Let the cake cool down for 15 minutes in the pan before transferring it to a cooling rack.
• Cool completely before slicing, and decorate with icing sugar if desired.

Storage

• Store leftovers in an airtight cake box in the fridge for up to 4 days or freeze for up to one month in sealed containers.