Grease and flour an 8" or 9" round springform pan, then sit to the side.
Pre-heat oven to 375 degrees.
Whisk milk, eggs, and vanilla together, then sit to the side.
In a large bowl, mix flour, baking powder, salt, and cinnamon.
Add diced butter to the bowl and mix with hands. Pinch butter pieces until they are pea size.
Stir in sugar and brown sugar.
Stir in apples and walnuts.
Pour in your liquid mixture and combine until there is no more dry ingredients.
Mixture will be dough-like, this is ok.
Pour mixture into your prepared cake pan.
Sprinkle cinnamon and sugar on top.
Bake for 45-55 minutes. The middle should be completely cooked and pass the toothpick test.
