Preheat oven to 350.
Grease the wells of a 6 or 12 count donut pan with cooking spray, set aside.
In medium bowl cream together your butter and sugar until light and fluffy.
Add your egg, vanilla and yogurt and mix until combined.
In separate bowl whisk together flour, baking powder, salt, cinnamon and nutmeg.
Stir into the wet ingredients until combined.
Fold in your apples.
To make your Coffee Cake Crumble, mix together all ingredients until coarse crumbs form.
Using a large piping bag or a zip lock bag with the corner snipped off, fill with your batter.
Pip into greased donut pan (if using a 6 count, you will do 2 batches).
Sprinkle tops with the crumble mixture, press down slightly.
Bake for 15-20 minutes or until toothpick comes out clean and tops are golden.
Remove from pan and let cool on wire rack.
Mix together all your glaze ingredients and drizzle over tops of donuts.
I used a smaller donut pan (not mini), this recipe should make roughly 12 regular sized donuts give or take a few depending on how full you fill your wells.