Preheat the oven to 350 degrees F. Either prepare a 9 inch spring form pan with parchment paper or grease and dust with a gluten free flour.
In a bowl, stir together flours, sugar, baking powder, baking soda and salt.
In a seperate, large bowl , beat eggs, stir in yogurt, oil, half the lemon zest and cubed apples and cinnamon.
Add the dry ingredients to the wet and stir just until combined.
Scrape into the prepared pan and tap on the counter to remove air bubbles.
Combine the topping ingredients in a small bowl and sprinkle on top of the batter.
Bake in the middle rack for 50 minutes to an hour or until a cake tester comes out clean.
Cool before removing form the springform pan and serving.