Preheat oven to 350°F. Place parchment paper in an 8 inch square baking dish.
In a large bowl add the flour, cinnamon, baking soda, and salt. Stir to combine.
In a medium bowl, whisk brown sugar, oil, and egg together until well combined. Add applesauce and Greek yogurt and mix well.
Gradually add to the flour mixture then fold in the apples. Pour batter into prepared baking dish.
Combine the topping ingredients and sprinkle over batter. Press gently into the batter.
Bake 30-35 minutes until a toothpick inserted into the center comes out clean. Let cool before cutting into squares.
Enjoy!