Preheat the oven to 350°F (175°C).

Prepare the crumb topping by adding all the dry ingredients into a bowl. Use a knife to cut the butter into the dry ingredients. Then use clean hands 
to crumble the butter in to make big clumps.

Prepare the vegan egg according to the package directions.

Use a whisk or spoon to mix the vegan egg, vegan sour cream, vegan butter, non-dairy milk, and vanilla extract and mix together.

Then add in flour, baking powder, and sugar.

Mix the batter until it looks thick like frosting. Do not overmix the batter once it is 
combined.

Line a 9 inch square baking dish with parchment paper. 
Add the batter to the bottom and spread it around. It will be low, but it rises a lot in the oven. Then add the apples on top, and finally cover with the crumb topping.

Bake for 45-55 minutes or until the crumb topping is browned and toothpick comes out clean.

Cool for at least half hour to an hour.

Make the sugar glaze by whisking the together to make a thick glaze. You can add more or 
less water to get it to your desired consistency. Then drizzle on top of the cake.

Cut the take into however many pieces you like. I did 16 smaller squares.