Melt the vegan butter in a small saucepan or microwave. Mix in the brown sugar and cinnamon until smooth.
Pour the mixture into a greased 9-inch cake pan, spreading evenly to cover the bottom.
Peel, core, and slice the apples into thin slices, arranging them in a circular pattern in the cake pan.
Mix flour, baking powder, soda, salt, and cinnamon in a large bowl.
Mix brown sugar, melted vegan butter, non-dairy milk, apple cider vinegar, vanilla extract, and maple syrup in a separate bowl.
Mix the wet and dry ingredients, stirring gently until combined.
Pour the cake batter evenly over the apples in the pan.
Bake in a preheated oven at 350°F (175°C) for 35-40 minutes or until a toothpick comes out clean.
Let the cake sit in the pan and cool for about 10 minutes.
Place a serving plate over the pan and carefully flip the cake to reveal the caramelized apple topping.
Allow the cake to cool slightly before serving. Enjoy warm or at room temperature.