Put flours, cane sugar, baking powder and salt into a medium bowl. Whisk to mix and break up any clumps.
Make a little well in the middle and add in the milk, apple sauce, vinegar and vanilla.
Whisk again to combine and get a smooth batter.
Combine the coconut or brown sugar and cinnamon in a small bowl and set aside.
Pour half the batter into a prepared square pan. You can use 8 or 9 inch, the 9 inch just gives you a thinner cake. I use some butter or coconut oil (whatever I use for the streusel topping) to prepare the pan. If you are oil free make sure to use a non stick pan or parchment.
Sprinkle half of the dry streusel mix over the top of the batter.
Pour the rest of the batter over the streusel mix.
Top with the remaining dry streusel mix and then drizzle the melted butter (or whatever you use) over the top.
Bake at 350 for 38-40 minutes. Depending on your oven, your baking time may vary by a minute or two. Start checking it at 35 minutes and take out when a toothpick comes out clean and the top is just getting firm. Because of the nature of the streusel it will look a little gooey on top but that’s ok. Focus on the toothpick and make sure it has crumbs instead of batter coming out.
Let this cool in the pan, about an hour. If you cut it too early, then the inner streusel will be oozy. It still is delicious but won’t look as pretty!
Once cooled, devour!
Notes
I trialed these with many different sugars and cane sugar gave the best result for the main cake. You can use coconut sugar but it will give you darker color and slightly different flavor.
If using brown sugar, the grams are calculated with it not measured packed but spooned into the measuring cup.
If you want this oil and butter free, you can omit them fully or try using a touch of coconut milk over the top instead. The end result will be a little different but still delicious. Without any butter, the top rises more like a traditional cake and doesn’t have that signature gooey cinnamon streusel like topping.