Combine all of the streusel ingredients together in a medium bowl and set aside.
Preheat the oven to 350F and grease a 9x13" baking pan.
In a medium heavy-bottomed pot over medium-low heat, combine the apples, water, brown sugar and cinnamon and cook until the apples are soft but not broken down, about 15 minutes. Set aside to cool.
In a medium bowl, whisk together the flour, baking soda, baking powder and salt.
In a large bowl or stand mixer, beat the butter and sugar at high speed until light and fluffy. Add the eggs one at a time and beat until incorporated after each addition. Add the flour and yogurt mixtures alternately in 2 parts while mixing on low speed until mixed, scraping the sides of the bowl. Fold in the cooked apples.
Transfer the cake batter into the prepared pan and spread evenly.
Sprinkle the streusel evenly over the top and bake for 30-35 minutes or until a toothpick inserted in the centre comes out clean.
*I used BC Gala apples because they keep their shape but you can use another type.