Preheat the oven to 350 F / 180 C. Grease 8 inch / 20 cm baking pan.
To make the streusel add the dry ingredients to a medium bowl. Then add melted vegan butter and vanilla and stir until the mixture is combined, set aside.
To make the cake in a large bowl, cream together 4 tbsp vegan butter with the sugar until light and fluffy, add apple sauce. Finally, add vanilla and vegan yoghurt and beat again.
Then add the flour, baking soda, salt, and baking powder and stir until just combined.
Spread half the batter at the bottom of the pan. Spread the apple chunks evenly over the batter, then sprinkle about 1 cup of streusel over the apples. Spread the remaining batter over the streusel and on top spread the rest of the streusel.
Bake 35-40 minutes or until a fork inserted in the center comes out clean