Combine:
1 c all purpose flour
1 tsp baking powder
1/4 tsp baking soda
pinch of salt

Combine:
1/4 c butter, softened
1/2 c sugar

Combine and add to wet:
1 egg
1 tsp vanilla
1/4 c plain yogurt

2 c apples, cored and sliced

Topping:
1/3 c flour
1/4 c brown sugar
1 tsp cinnamon
1/4 c butter, softened

Add dry slowly to wet, mixing well.  Put batter in a 9 inch pan.  Lay apples over the top.  make topping.  Crumble that over the apples.  Cook at 350 for 20-30 minutes.